Prove that \(20^{2n}+16^{2n}-3^{2n-1}\)is divisible by 323.
It isn't!
Let n = 1
202 + 162 - 3 = 653
653/323 = 2.02167...
I think you must mean prove that \(20^{2n}+16^{2n}-3^{2n}-1\) is divisible by 323 for integer n
