Large Carmichael number












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I need to find or generate a very large Carmichael number (500 digits or longer). I've tried to find a database or just an example of such a number but failed. Is there any examples of really big Carmichael numbers or an implementation of an algorithm I'd be able to run locally?










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    $begingroup$


    I need to find or generate a very large Carmichael number (500 digits or longer). I've tried to find a database or just an example of such a number but failed. Is there any examples of really big Carmichael numbers or an implementation of an algorithm I'd be able to run locally?










    share|cite|improve this question









    $endgroup$















      2












      2








      2





      $begingroup$


      I need to find or generate a very large Carmichael number (500 digits or longer). I've tried to find a database or just an example of such a number but failed. Is there any examples of really big Carmichael numbers or an implementation of an algorithm I'd be able to run locally?










      share|cite|improve this question









      $endgroup$




      I need to find or generate a very large Carmichael number (500 digits or longer). I've tried to find a database or just an example of such a number but failed. Is there any examples of really big Carmichael numbers or an implementation of an algorithm I'd be able to run locally?







      number-theory algorithms carmichael-numbers






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      asked Dec 7 '18 at 11:22









      NikromNikrom

      1376




      1376






















          1 Answer
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          $begingroup$

          Probably the best approach is to search a positive integer $k$, such that $6k+1$ , $12k+1$ , $18k+1$ are all prime. Then $$N=(6k+1)(12k+1)(18k+1)$$ is a Carmichael-number. If you find $k>10^{170}$ with the desired property , you are done.






          share|cite|improve this answer











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          • $begingroup$
            For example , $$k=10^{170}+8786356$$ does the job
            $endgroup$
            – Peter
            Dec 7 '18 at 11:56










          • $begingroup$
            I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
            $endgroup$
            – gammatester
            Dec 7 '18 at 12:04












          • $begingroup$
            I tested the factors with the APR-test. They are in fact all prime.
            $endgroup$
            – Peter
            Dec 7 '18 at 12:06










          • $begingroup$
            hal.inria.fr/inria-00076980/document could be of interest to you.
            $endgroup$
            – Claude Leibovici
            Dec 7 '18 at 12:25











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          1 Answer
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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

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          active

          oldest

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          2












          $begingroup$

          Probably the best approach is to search a positive integer $k$, such that $6k+1$ , $12k+1$ , $18k+1$ are all prime. Then $$N=(6k+1)(12k+1)(18k+1)$$ is a Carmichael-number. If you find $k>10^{170}$ with the desired property , you are done.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            For example , $$k=10^{170}+8786356$$ does the job
            $endgroup$
            – Peter
            Dec 7 '18 at 11:56










          • $begingroup$
            I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
            $endgroup$
            – gammatester
            Dec 7 '18 at 12:04












          • $begingroup$
            I tested the factors with the APR-test. They are in fact all prime.
            $endgroup$
            – Peter
            Dec 7 '18 at 12:06










          • $begingroup$
            hal.inria.fr/inria-00076980/document could be of interest to you.
            $endgroup$
            – Claude Leibovici
            Dec 7 '18 at 12:25
















          2












          $begingroup$

          Probably the best approach is to search a positive integer $k$, such that $6k+1$ , $12k+1$ , $18k+1$ are all prime. Then $$N=(6k+1)(12k+1)(18k+1)$$ is a Carmichael-number. If you find $k>10^{170}$ with the desired property , you are done.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            For example , $$k=10^{170}+8786356$$ does the job
            $endgroup$
            – Peter
            Dec 7 '18 at 11:56










          • $begingroup$
            I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
            $endgroup$
            – gammatester
            Dec 7 '18 at 12:04












          • $begingroup$
            I tested the factors with the APR-test. They are in fact all prime.
            $endgroup$
            – Peter
            Dec 7 '18 at 12:06










          • $begingroup$
            hal.inria.fr/inria-00076980/document could be of interest to you.
            $endgroup$
            – Claude Leibovici
            Dec 7 '18 at 12:25














          2












          2








          2





          $begingroup$

          Probably the best approach is to search a positive integer $k$, such that $6k+1$ , $12k+1$ , $18k+1$ are all prime. Then $$N=(6k+1)(12k+1)(18k+1)$$ is a Carmichael-number. If you find $k>10^{170}$ with the desired property , you are done.






          share|cite|improve this answer











          $endgroup$



          Probably the best approach is to search a positive integer $k$, such that $6k+1$ , $12k+1$ , $18k+1$ are all prime. Then $$N=(6k+1)(12k+1)(18k+1)$$ is a Carmichael-number. If you find $k>10^{170}$ with the desired property , you are done.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Dec 7 '18 at 11:45

























          answered Dec 7 '18 at 11:39









          PeterPeter

          48.6k1139136




          48.6k1139136












          • $begingroup$
            For example , $$k=10^{170}+8786356$$ does the job
            $endgroup$
            – Peter
            Dec 7 '18 at 11:56










          • $begingroup$
            I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
            $endgroup$
            – gammatester
            Dec 7 '18 at 12:04












          • $begingroup$
            I tested the factors with the APR-test. They are in fact all prime.
            $endgroup$
            – Peter
            Dec 7 '18 at 12:06










          • $begingroup$
            hal.inria.fr/inria-00076980/document could be of interest to you.
            $endgroup$
            – Claude Leibovici
            Dec 7 '18 at 12:25


















          • $begingroup$
            For example , $$k=10^{170}+8786356$$ does the job
            $endgroup$
            – Peter
            Dec 7 '18 at 11:56










          • $begingroup$
            I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
            $endgroup$
            – gammatester
            Dec 7 '18 at 12:04












          • $begingroup$
            I tested the factors with the APR-test. They are in fact all prime.
            $endgroup$
            – Peter
            Dec 7 '18 at 12:06










          • $begingroup$
            hal.inria.fr/inria-00076980/document could be of interest to you.
            $endgroup$
            – Claude Leibovici
            Dec 7 '18 at 12:25
















          $begingroup$
          For example , $$k=10^{170}+8786356$$ does the job
          $endgroup$
          – Peter
          Dec 7 '18 at 11:56




          $begingroup$
          For example , $$k=10^{170}+8786356$$ does the job
          $endgroup$
          – Peter
          Dec 7 '18 at 11:56












          $begingroup$
          I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
          $endgroup$
          – gammatester
          Dec 7 '18 at 12:04






          $begingroup$
          I can confirm that it is a (probable) Carmichael number using a Pascal implementation of the algorithm from math.stackexchange.com/a/1729144/61216
          $endgroup$
          – gammatester
          Dec 7 '18 at 12:04














          $begingroup$
          I tested the factors with the APR-test. They are in fact all prime.
          $endgroup$
          – Peter
          Dec 7 '18 at 12:06




          $begingroup$
          I tested the factors with the APR-test. They are in fact all prime.
          $endgroup$
          – Peter
          Dec 7 '18 at 12:06












          $begingroup$
          hal.inria.fr/inria-00076980/document could be of interest to you.
          $endgroup$
          – Claude Leibovici
          Dec 7 '18 at 12:25




          $begingroup$
          hal.inria.fr/inria-00076980/document could be of interest to you.
          $endgroup$
          – Claude Leibovici
          Dec 7 '18 at 12:25


















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