\begin{definition}[Definition:Heptagonal Number/Sequence]
The sequence of heptagonal numbers, for $n \in \Z_{\ge 0}$, begins:
:$0, 1, 7, 18, 34, 55, 81, 112, 148, 189, 235, 286, 342, 403, 469, 540, \ldots$
{{OEIS|A000566}}
\end{definition}