Problem 6 of RMO 2006 (Regional Mathematical Olympiad-India)
Source: Elementry Number Theory
September 13, 2009
searchnumber theory unsolvednumber theory
Problem Statement
Prove that there are infinitely many positive integers such that n(n\plus{}1) can be represented as a sum of two positive squares in at least two different ways. (Here a^{2}\plus{}b^{2} and b^{2}\plus{}a^{2} are considered as the same representation.)