6m|(2m + 3)^n+1 if and only if 4m|3^n+1
Source: Vietnam TST 2008, Problem 4
April 10, 2008
number theory proposednumber theory
Problem Statement
Let and be positive integers. Prove that 6m | (2m \plus{} 3)^n \plus{} 1 if and only if 4m | 3^n \plus{} 1