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 A118565 #6 Oct 31 2013 12:17:38
%S A118565 1,3,15,21,105,171,231,741,903,1275,1485,1711,2211,2415,3003,3403,
%T A118565 3655,4095,4465,4851,5151,5253,5671,7503,8001,8515,10153,10585,10731,
%U A118565 11781,13203,13695,13861,17391,18145,18915,19503,21115,22155,22791,24531
%N A118565 Numbers which are both lucky and triangular.
%H A118565 Donovan Johnson, <a href="/A118565/b118565.txt">Table of n, a(n) for n = 1..3537</a>
%t A118565 triQ[n_] := IntegerQ@Sqrt[8n+1]; lst = Range[1, 26564, 2]; i = 2; While[ i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; Select[lst, triQ@# &] (* _Robert G. Wilson v_ *)
%Y A118565 Cf. A000959, A000217.
%K A118565 nonn
%O A118565 1,2
%A A118565 Luc Stevens (lms022(AT)yahoo.com), May 07 2006
%E A118565 Corrected and extended by Adam Panagos (adam.panagos(AT)gmail.com) and _Robert G. Wilson v_, May 10 2006