"any number" means that you must be able to produce two triangles if asked for two, three if asked for three, four if asked for four, 7 trillion if asked for 7 trillion, etc. Effectively, you have to be able to generate infinitely many (technically: aleph-0) Pythagorean triangles.

Aside: I do not think that is a the nice problem, as there are way easier ways to generate aleph-0 such triangles (I think most mathematicians would agree the simplest is 3x,4x,5x for x in {1,2,...}) But that is not what this question is hinting at.