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Math Help - mersenne primes

  1. #1
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    mersenne primes

    I understand how you find these primes but how do you prove it? It seems so simple because you can just plug in numbers but thats not a mathematical proof.


    Prove that if (2^n)-1 is prime, then n is prime.
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  2. #2
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    Quote Originally Posted by hero View Post
    I understand how you find these primes but how do you prove it? It seems so simple because you can just plug in numbers but thats not a mathematical proof.


    Prove that if (2^n)-1 is prime, then n is prime.
    Simple. Use my hint below.

    Hint1: If n>1 is not prime then n=a*b where 1<a,b

    Hint2: Use the identity, (x^n-y^n)=(x-y)(x^{n-1}+x^{n-2}y+...+y^{n-1})
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