Math, Recursion, Recurrent Relations, Generating Functions, Discrete Mathematics.
The coefficients of x are the solution So we proved that a_n = a_{n-1} + 1 = n where a_0 = 0. That took quite some gymnastics to do! The good news is that the method of generating functions is systematic and has no guessing, unlike guessing and checking with induction. Thus, it can be used to solve