Ordinary generating function
= Ordinary generating function
{title2=$A(z)=\sum_{n\geq0}a_nz^n$}
{wiki=Generating_function}
The ordinary generating function of a sequence $(a_n)_{n\geq0}$ is the <formal power series> $A(z)=\sum_{n\geq0}a_nz^n$. Algebraic identities for $A$ encode recurrences and counting constructions for the coefficients.