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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
Message 1 of 4 , Jan 18, 2005
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
• 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
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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