1,1

Peter Kagey, Table of n, a(n) for n = 1..10000

Cf. A000326 (pentagonal numbers).

Analogs are A000404 (square numbers), A051533 (triangular numbers), A286636 (centered square numbers), A287960 (centered triangular numbers), A288631 (square pyramidal numbers).

Sequence in context: A247785 A190701 A184918 * A023419 A183990 A049838

Adjacent sequences: A332984 A332985 A332986 * A332988 A332989 A332990

nonn

Olivier Gérard, Mar 05 2020

approved