Problems & Puzzles:
2^n-2^k+1, a square
Sebastian Martin Ruiz sent the following
For all even n exists k that 2^n-2^k+1 is a
Is trivial k=n/2+1 then 2^n-2^(n/2+1)+1=(2^(n/2)-1)^2.
But for odd n ?
I have obtained only three solutions:
Q1. Can you find solutions other than
5, 7 & 15?
Q2. Is always k=3?