IMO Shortlist 2003 problem N5
Dodao/la: arhiva2. travnja 2012.
is said to be good if
is not the square of an integer. Determine all integers
with the following property:
can be represented, in infinitely many ways, as a sum of three distinct good integers whose product is the square of an odd integer.
Izvor: Međunarodna matematička olimpijada, shortlist 2003