1. Forum
  2. Usenet
  3. REC.PUZZLES

  • if p is prime, then so is (2^p - 1)

    From henhanna@gmail.com@21:1/5 to All on Sat Aug 13 11:08:53 2022
    (no need to "wait a few days, before..." ------ this must've be known for Centuries)


    Are the following both true ?

    A. if p is prime, then so is (2^p - 1)

    ---------- for what kind of P does this fail ?


    B. if (2^p - 1) is prime, then so is p.




    ( 2018年2月現在、50個のメルセンヌ素数が発見されている。 )

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Kerr-Mudd, John@21:1/5 to henh...@gmail.com on Sat Aug 13 19:28:51 2022
    On Sat, 13 Aug 2022 11:08:53 -0700 (PDT)
    "henh...@gmail.com" <henhanna@gmail.com> wrote:

    (no need to "wait a few days, before..." ------ this must've be known for Centuries)


    Are the following both true ?

    A. if p is prime, then so is (2^p - 1)

    ---------- for what kind of P does this fail ?


    B. if (2^p - 1) is prime, then so is p.


    It's quite a Little Puzzle

    https://en.wikipedia.org/wiki/Fermat%27s_little_theorem



    Please try harder.

    --
    Bah, and indeed Humbug.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Eric Sosman@21:1/5 to John on Sat Aug 13 15:45:00 2022
    On 8/13/2022 2:28 PM, Kerr-Mudd, John wrote:
    On Sat, 13 Aug 2022 11:08:53 -0700 (PDT)
    "henh...@gmail.com" <henhanna@gmail.com> wrote:

    (no need to "wait a few days, before..." ------ this must've be known for Centuries)


    Are the following both true ?

    A. if p is prime, then so is (2^p - 1)

    ---------- for what kind of P does this fail ?


    B. if (2^p - 1) is prime, then so is p.


    It's quite a Little Puzzle

    https://en.wikipedia.org/wiki/Fermat%27s_little_theorem



    Please try harder.

    ... or at least let it marin-ate a bit longer.

    --
    esosman@comcast-dot-net.invalid
    Look on my code, ye Hackers, and guffaw!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)