Math Is Fun Forum

Primenumbers

Member

Registered: 2013-01-22

Posts: 149

If 2p + 1 is a factor of 2^p - 1 then it is prime, proof.

If an integer, 2p + 1, where p is a prime number, is a divisor of the Mersenne number

, then 2p + 1 is a prime number.

My argument is that because divisors of the Mersenne number

can’t be < p if p is a prime number. Therefore if 2p +1 is a divisor of

it has no divisors as p is > the square root of 2p + 1. This will therefore make 2p + 1 a prime number.

Is this proof correct?

Last edited by Primenumbers (2019-01-13 03:42:20)

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"Time not important. Only life important." - The Fifth Element 1997