MathDB
VMO 2015 Problem 6

Source: VMO 2015

July 31, 2016
number theory

Problem Statement

For a,nZ+a,n\in\mathbb{Z}^+, consider the following equation: a^2x+6ay+36z=n  (1) where x,y,zNx,y,z\in\mathbb{N}.
a) Find all aa such that for all n250n\geq 250, (1)(1) always has natural roots (x,y,z)(x,y,z).
b) Given that a>1a>1 and gcd(a,6)=1\gcd (a,6)=1. Find the greatest value of nn in terms of aa such that (1)(1) doesn't have natural root (x,y,z)(x,y,z).