MathDB
d|a^2+2, find d mod 8

Source: VJIMC 1997 1.1

September 26, 2021
number theory

Problem Statement

Let aa be an odd positive integer. Prove that if dd divides a2+2a^2+2, then d1(mod8)d\equiv1\pmod8 or d3(mod8)d\equiv3\pmod8.