IMO 2009 Shortlist A3
Determine all functions f from the set of positive integers into the set of positive integers such that for all x and y ...
Category: Algebra
Problem
Determine all functions f from the set of positive integers into the set of positive integers such that for all x and y there exists a non degenerated triangle with sides of lengths x, f(y) and f(y + f(x) − 1).