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Re: [PrimeNumbers] Re: Number 19

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  • Makoto Kamada
    ... According to Patrick de Geest s website, Hans Rosenthal found it. http://www.worldofnumbers.com/undulat.htm#supp919 Factorizations of (91*10^(2n+1)-19)/99
    Message 1 of 5 , Sep 10, 2010
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      On 2010/09/10 21:20, LĂ©lio Ribeiro de Paula wrote:
      >> --- In primenumbers@yahoogroups.com, David Broadhurst wrote:
      >>
      >> The next probable prime has 25229 digits:
      >>
      >> (91*10^25229-19)/99 is Fermat and Lucas PRP! (166.8607s+0.0024s)
      >
      > and was found by Patrick de Geest in july 2004:
      >
      > http://www.primenumbers.net/prptop/searchform.php?form=%3F%2F99

      According to Patrick de Geest's website, Hans Rosenthal found it.
      http://www.worldofnumbers.com/undulat.htm#supp919

      Factorizations of (91*10^(2n+1)-19)/99 are here:
      http://www.asahi-net.or.jp/~kc2h-msm/mathland/aba/aba919.htm

      Makoto Kamada
    • maximilian_hasler
      ... The 15 digit number 151515151515151 is prime, too ; and it is the only such prime (undulating : aba...ba with ab = 10*a+b or ba = 10*b+a digits. M.
      Message 2 of 5 , Sep 10, 2010
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        > 23 digits 91919191919191919191919 is prime
        > 17 digits 91919191919191919 is prime.
        > 11 digits 91919191919 is prime.
        > 9 digits 919191919 is prime.

        The 15 digit number 151515151515151 is prime, too ;
        and it is the only such prime (undulating : aba...ba
        with ab = 10*a+b or ba = 10*b+a digits.

        M.
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