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Re: [PrimeNumbers] One kind of prime numbers

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  • Jens Kruse Andersen
    ... Two different names are used: emirp (prime backwards) and reversible prime . The definition usually excludes palindromes. The largest known are at
    Message 1 of 6 , Apr 20, 2006
      Jose C. Martinez wrote:

      > I wanted to know how are called those primes numbers that when are
      > readed from left to right and from right to left both number are
      > primes.

      Two different names are used:
      "emirp" (prime backwards) and "reversible prime".
      The definition usually excludes palindromes.

      The largest known are at http://www.primepuzzles.net/puzzles/puzz_020.htm
      (Only a few GHz days work).

      This weeks puzzle is also about them:
      http://www.primepuzzles.net/puzzles/puzz_357.htm

      --
      Jens Kruse Andersen
    • Phil Carmody
      ... 101, hmmmm - sounds totally tetradic to me! Phil () ASCII ribbon campaign () Hopeless ribbon campaign / against HTML mail / against
      Message 2 of 6 , Apr 20, 2006
        --- "Jose C. Martinez" <jcmtnez90@...> wrote:
        > I wanted to know how are called those primes numbers that when are
        > readed from left to right and from right to left both number are
        > primes.
        > For example
        >
        > 13-31
        > 17-71
        > 37-73
        > 79-97
        > 101-101

        101, hmmmm - sounds totally tetradic to me!

        Phil

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