This document discusses mathematical generating functions. It defines a generating function as treating the coefficients of an infinite sequence as coefficients in a series expansion, with the sum of the series being the generating function. It discusses ordinary generating functions specifically, where the generating function is a power series representing a sequence. Some examples of sequences and their generating functions are given. It also notes that adding leading zeros to a sequence corresponds to multiplying the generating function by x to the power of the number of zeros added, known as a right shift rule.