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[PrimeNumbers] prime product

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  • Will Edgington
    let p be a prime number and r is product of all primes from2 including p r=2*3*5*7*......*p s is anumber so that s r+1 and s is prime. If t=s-r then t is
    Message 1 of 4 , Jan 18, 2005
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      let p be a prime number and r is product of all primes from2 including p
      r=2*3*5*7*......*p s is anumber so that s>r+1 and s is prime. If
      t=s-r then t is prime. Is this fact proved?

      No, and it can't be. Let p = 3 and s = 31. Then t is 25.

      Will

      http://www.garlic.com/~wedgingt/mersenne.html
    • mikeoakes2@aol.com
      In a message dated 18/01/2005 19:55:40 GMT Standard Time, mcnamara_gio@yahoo.com writes: let p be a prime number and r is product of all primes from2
      Message 2 of 4 , Jan 18, 2005
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        In a message dated 18/01/2005 19:55:40 GMT Standard Time,
        mcnamara_gio@... writes:

        let p be a prime number and r is product of all primes from2 including p
        r=2*3*5*7*......*p s is anumber so that s>r+1 and s is prime. If
        t=s-r then t is prime. Is this fact proved?



        No, because it is false.
        Take p = , so r = 210.
        Take s=331 which is >211 and prime.
        Then t = s-r=121 which is not prime.

        Time taken to find this exception with a list of small primes: 1.5 mins.

        Perhaps you could have had the fun of doing a quick check before posting?

        -Mike Oakes



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