Prove that, for any positive integer $n$, $$1^n+2^n+3^n+4^n$$ is divisible by $5
Source: Eotvos 1901 p1
March 19, 2020
algebra
Problem Statement
Prove that, for any positive integer , is divisible by if and only if is not divisible by .
Source: Eotvos 1901 p1