MathDB
4ab/(ab^2+1) is a natural

Source: Mathcenter Contest / Oly - Thai Forum 2009 R2 p2 https://artofproblemsolving.com/community/c3196914_mathcenter_contest

November 9, 2022
number theory

Problem Statement

Find all natural numbers that can be written in the form 4abab2+1\frac{4ab}{ab^2+1} for some natural a,ba,b.
(nooonuii)