Pentagonal Number/Sequence

Definition

The sequence of pentagonal numbers, for $n \in \Z_{\ge 0}$, begins:

$0, 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, 176, \ldots$

This sequence is A000326 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $22$
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): Tables: $2$ The First $20$ Pentagonal, Hexagonal, Heptagonal and Octagonal Numbers
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $22$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): Tables: $2$ The First $20$ Pentagonal, Hexagonal, Heptagonal and Octagonal Numbers
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): pentagonal number
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): pentagonal number