MathDB
Ibero American 2012 - Problem 4

Source:

October 3, 2012
inductionmodular arithmeticstrong inductionalgebra proposedalgebra

Problem Statement

Let a,b,c,da,b,c,d be integers such that the number ab+cda-b+c-d is odd and it divides the number a2b2+c2d2a^2-b^2+c^2-d^2. Show that, for every positive integer nn, ab+cda-b+c-d divides anbn+cndna^n-b^n+c^n-d^n.