This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A117795 #8 Dec 02 2019 20:39:53 %S A117795 0,7,112,189,469,616,1071,1288,1918,2205,3010,3367,4347,4774,5929, %T A117795 6426,7756,8323,9828,10465,12145,12852,14707,15484,17514,18361,20566, %U A117795 21483,23863,24850,27405,28462,31192,32319,35224,36421,39501,40768,44023 %N A117795 Heptagonal numbers divisible by 7. %C A117795 Intersection of A000566 and A008589. Their indices are given by A047352. - _Michel Marcus_, Feb 27 2014 %H A117795 Harvey P. Dale, <a href="/A117795/b117795.txt">Table of n, a(n) for n = 1..1000</a> %t A117795 Select[PolygonalNumber[7,Range[0,200]],Divisible[#,7]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 02 2019 *) %o A117795 (PARI) isok(n) = ispolygonal(n, 7) && !(n % 7); \\ _Michel Marcus_, Feb 27 2014 %Y A117795 Cf. A000566, A008589, A047352. %K A117795 easy,nonn %O A117795 1,2 %A A117795 Luc Stevens (lms022(AT)yahoo.com), Apr 29 2006