A117795 Heptagonal numbers divisible by 7.

0, 7, 112, 189, 469, 616, 1071, 1288, 1918, 2205, 3010, 3367, 4347, 4774, 5929, 6426, 7756, 8323, 9828, 10465, 12145, 12852, 14707, 15484, 17514, 18361, 20566, 21483, 23863, 24850, 27405, 28462, 31192, 32319, 35224, 36421, 39501, 40768, 44023

Offset: 1

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 29 2006

Keywords

• easy
• nonn

Comments

Intersection of A000566 and A008589. Their indices are given by A047352. - Michel Marcus, Feb 27 2014

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000566, A008589, A047352.

Programs

Mathematica

Select[PolygonalNumber[7,Range[0,200]],Divisible[#,7]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 02 2019 *)

PARI

isok(n) = ispolygonal(n, 7) && !(n % 7); \\ Michel Marcus, Feb 27 2014