Generalized Pentagonal Number/Sequence

Sequence of Generalized Pentagonal Numbers
The sequence of generalized pentagonal numbers, for $n \in \Z_{\ge 0}$, begins:
 * $P_n = 0, 1, 2, 5, 7, 12, 15, 22, 26, 35, 40, 51, 57, 70, 77, 92, 100, \ldots$