A117798 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A117798

Icosagonal numbers divisible by 20.

0, 20, 820, 1200, 3440, 4180, 7860, 8960, 14080, 15540, 22100, 23920, 31920, 34100, 43540, 46080, 56960, 59860, 72180, 75440, 89200, 92820, 108020, 112000, 128640, 132980, 151060, 155760, 175280, 180340, 201300, 206720, 229120, 234900, 258740

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Intersection of A008602 and A051872. - Michel Marcus, Feb 27 2014

LINKS

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Table[PolygonalNumber[20, n], {n, 0, 200}], Divisible[#, 20] &] (* Amiram Eldar, Mar 22 2021 *)

PROG

(PARI) isok(n) = ispolygonal(n, 20) && !(n % 20); \\ Michel Marcus, Feb 27 2014

CROSSREFS