1. The problem statement, all variables and given/known data If M and N are positive integers >2, prove that ((2^m)-1) is not a divisor of ((2^n)+1) 2. Relevant equations 3. The attempt at a solution Is this correct? I use the well-ordering principle. Let T be the set of all M,N positive integers greater than 2 such that ((2^m)-1)/((2^n)+1). Assume T is non-empty, then by the WOP, T must contain a smallest L element, call it((2^k)-1)/((2^L)+1). but (2^(k+1)-1)/(2^(L+1)+1) is in T. So, ((2^k)*(2^1)-1)/((2^L)*(2^1)+1). Thus, I have a contradiction.