A332987 Sums of two nonzero pentagonal numbers.

2, 6, 10, 13, 17, 23, 24, 27, 34, 36, 40, 44, 47, 52, 56, 57, 63, 70, 71, 73, 75, 82, 86, 92, 93, 97, 102, 104, 105, 114, 118, 121, 122, 127, 129, 139, 140, 143, 146, 150, 152, 157, 162, 167, 168, 177, 180, 181, 184, 187, 188, 196, 198, 209, 211, 215, 222, 227

Offset: 1

Author

Olivier Gérard, Mar 05 2020

Keywords

• nonn

Links

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

Crossrefs

Cf. A000326 (pentagonal numbers).

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

Programs

Mathematica

Module[{nn=15,pn},pn=PolygonalNumber[5,Range[nn]];Select[Union[ Total/@ Tuples[ pn,2]],#<=Last[pn]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 15 2021 *)