A 4 x 4 Magic Square with Pairwise Relatively Prime Entries












7












$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    Feb 10 at 14:56










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 14:59










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    Feb 10 at 20:51










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 21:54






  • 1




    $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    Feb 11 at 0:08
















7












$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    Feb 10 at 14:56










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 14:59










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    Feb 10 at 20:51










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 21:54






  • 1




    $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    Feb 11 at 0:08














7












7








7


1



$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$




Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?







mathematics computer-puzzle magic-square






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Feb 10 at 21:57









Jonathan Allan

17.9k14697




17.9k14697










asked Feb 10 at 14:31









Bernardo Recamán SantosBernardo Recamán Santos

2,4991344




2,4991344












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    Feb 10 at 14:56










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 14:59










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    Feb 10 at 20:51










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 21:54






  • 1




    $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    Feb 11 at 0:08


















  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    Feb 10 at 14:56










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 14:59










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    Feb 10 at 20:51










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    Feb 10 at 21:54






  • 1




    $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    Feb 11 at 0:08
















$begingroup$
What is “pairwise different”?
$endgroup$
– Arvasu Kulkarni
Feb 10 at 14:56




$begingroup$
What is “pairwise different”?
$endgroup$
– Arvasu Kulkarni
Feb 10 at 14:56












$begingroup$
@ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
$endgroup$
– Bernardo Recamán Santos
Feb 10 at 14:59




$begingroup$
@ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
$endgroup$
– Bernardo Recamán Santos
Feb 10 at 14:59












$begingroup$
Was this puzzle of your own creation?
$endgroup$
– Brandon_J
Feb 10 at 20:51




$begingroup$
Was this puzzle of your own creation?
$endgroup$
– Brandon_J
Feb 10 at 20:51












$begingroup$
@Brandon_J: An oldie twisted.
$endgroup$
– Bernardo Recamán Santos
Feb 10 at 21:54




$begingroup$
@Brandon_J: An oldie twisted.
$endgroup$
– Bernardo Recamán Santos
Feb 10 at 21:54




1




1




$begingroup$
Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
$endgroup$
– kkm
Feb 11 at 0:08




$begingroup$
Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
$endgroup$
– kkm
Feb 11 at 0:08










3 Answers
3






active

oldest

votes


















3












$begingroup$

I believe this is optimal (unless I've missed a trick):





  1 13 47 53
29 59 7 19
41 11 37 25
43 31 23 17



Which has




a maximal value of 59 (and a sum of 114)


Note: all values are prime except for 1 and the composite number 25




I also found these two with the same maximum value:





  1 17 37 59
53 29 23 9
47 19 43 5
13 49 11 41
...using primes, 1, 9 and 49 (with a sum of 114);

and
  1 29 47 49
43 41 37 5
59 17 31 19
23 39 11 53
...using primes, 1, 39 and 49 (with a sum of 126)




First I found these two:





 1 11 41 61
47 31 17 19
43 13 53 5
23 59 3 29
and
 1 13 47 53
29 59 7 19
61 31 17 5
23 11 43 37
both of which have a maximal value of 61 (and a sum of 114)


For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






share|improve this answer











$endgroup$













  • $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    Feb 10 at 22:22










  • $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    Feb 10 at 22:25












  • $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:35












  • $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    Feb 10 at 22:35










  • $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:40



















3












$begingroup$

I've got a solution:




and I admit I found it online.




Here it is:




Magic Square




The largest number in it is




73







share|improve this answer











$endgroup$













  • $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 20:56










  • $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    Feb 10 at 20:56










  • $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:00










  • $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    Feb 10 at 21:04










  • $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:06



















1












$begingroup$

The following magic square





 11  1 53 37
7 47 29 19
71 23 3 5
13 31 17 41



has magic constant




102




and largest number




71







share|improve this answer









$endgroup$













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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$













    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      Feb 10 at 22:22










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      Feb 10 at 22:25












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:35












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      Feb 10 at 22:35










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:40
















    3












    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$













    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      Feb 10 at 22:22










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      Feb 10 at 22:25












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:35












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      Feb 10 at 22:35










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:40














    3












    3








    3





    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$



    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Feb 10 at 23:57

























    answered Feb 10 at 22:11









    Jonathan AllanJonathan Allan

    17.9k14697




    17.9k14697












    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      Feb 10 at 22:22










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      Feb 10 at 22:25












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:35












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      Feb 10 at 22:35










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:40


















    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      Feb 10 at 22:22










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      Feb 10 at 22:25












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:35












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      Feb 10 at 22:35










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      Feb 10 at 22:40
















    $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    Feb 10 at 22:22




    $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    Feb 10 at 22:22












    $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    Feb 10 at 22:25






    $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    Feb 10 at 22:25














    $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:35






    $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:35














    $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    Feb 10 at 22:35




    $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    Feb 10 at 22:35












    $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:40




    $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    Feb 10 at 22:40











    3












    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$













    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 20:56










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      Feb 10 at 20:56










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:00










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      Feb 10 at 21:04










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:06
















    3












    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$













    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 20:56










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      Feb 10 at 20:56










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:00










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      Feb 10 at 21:04










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:06














    3












    3








    3





    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$



    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73








    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Feb 10 at 20:49

























    answered Feb 10 at 20:30









    Brandon_JBrandon_J

    1,653228




    1,653228












    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 20:56










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      Feb 10 at 20:56










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:00










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      Feb 10 at 21:04










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:06


















    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 20:56










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      Feb 10 at 20:56










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:00










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      Feb 10 at 21:04










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      Feb 10 at 21:06
















    $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 20:56




    $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 20:56












    $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    Feb 10 at 20:56




    $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    Feb 10 at 20:56












    $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:00




    $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:00












    $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    Feb 10 at 21:04




    $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    Feb 10 at 21:04












    $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:06




    $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    Feb 10 at 21:06











    1












    $begingroup$

    The following magic square





     11  1 53 37
    7 47 29 19
    71 23 3 5
    13 31 17 41



    has magic constant




    102




    and largest number




    71







    share|improve this answer









    $endgroup$


















      1












      $begingroup$

      The following magic square





       11  1 53 37
      7 47 29 19
      71 23 3 5
      13 31 17 41



      has magic constant




      102




      and largest number




      71







      share|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        The following magic square





         11  1 53 37
        7 47 29 19
        71 23 3 5
        13 31 17 41



        has magic constant




        102




        and largest number




        71







        share|improve this answer









        $endgroup$



        The following magic square





         11  1 53 37
        7 47 29 19
        71 23 3 5
        13 31 17 41



        has magic constant




        102




        and largest number




        71








        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Feb 11 at 0:17









        Freddy BarreraFreddy Barrera

        34318




        34318






























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