Hi, I'm needing some help with an exercise

Let A be {k^2|k belongs to N}. I need to if A holds the following proposition: "For every n that belongs to N, if n belongs to A then n+1 belongs to A."

My problem is on the way the set is defined, as far as I understand it, A should be {1,4,9,16,25,36...}.

I will appreciate any response as long as it doesn't reveal the solution to the problem... tnx in advance...