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 A259165 #18 Aug 16 2015 12:04:01
%S A259165 540,125482435,29152330292086,6772727677992549813,
%T A259165 1573453639577432827392256,365547896447135621647431177175,
%U A259165 84924818396817988252797073116286650,19729903659220000770419185998874515952681,4583690677832384200588508141377728222042497188
%N A259165 Positive heptagonal numbers (A000566) that are pentagonal numbers (A000326) divided by 2.
%C A259165 Intersection of A000566 and A193866 (even pentagonal numbers divided by 2). - _Michel Marcus_, Jun 20 2015
%H A259165 Colin Barker, <a href="/A259165/b259165.txt">Table of n, a(n) for n = 1..186</a>
%H A259165 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (232323,-232323,1).
%F A259165 G.f.: -x*(x^2+28015*x+540) / ((x-1)*(x^2-232322*x+1)).
%e A259165 540 is in the sequence because 540 is the 15th heptagonal number, and 2*540 is the 27th pentagonal number.
%t A259165 LinearRecurrence[{232323, -232323, 1}, {540, 125482435, 29152330292086}, 20] (* _Vincenzo Librandi_, Jun 20 2015 *)
%o A259165 (PARI) Vec(-x*(x^2+28015*x+540)/((x-1)*(x^2-232322*x+1)) + O(x^20))
%Y A259165 Cf. A000326, A000566, A193866, A259156-A259164, A259166, A259167.
%K A259165 nonn,easy
%O A259165 1,1
%A A259165 _Colin Barker_, Jun 19 2015