http://prntscr.com/lvnkkp

For the first one, answer is 65, because 64=4^3.

For the second one, answer is 18, because 3^2=9, 3^3=27, and 3^4=81.

1. We subtract one from each power: 9, 25, 36, 64. Now, taking the prime factorizations, we have \(3^2, 5^2, 2^2*3^2, 2^6\) . By scanning, we can see that 64 is a cube number, therefore 65 is our answer.