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 A292610 #13 Sep 25 2017 07:50:14 %S A292610 1,3,6,15,21,28,36,66,78,91,105,120,190,210,231,253,276,300,435,465, %T A292610 496,528,561,595,630,861,903,946,990,1035,1081,1128,1176,1540,1596, %U A292610 1653,1711,1770,1830,1891,1953,2016,2556,2628,2701,2775,2850,2926,3003,3081,3160,3240 %N A292610 Take 3 triangle numbers, skip 1 triangle number, take 4 triangle numbers, skip 2 triangle numbers, take 5 triangle numbers, skip 3 triangle numbers, ... %H A292610 Seiichi Manyama, <a href="/A292610/b292610.txt">Table of n, a(n) for n = 1..10000</a> %t A292610 Block[{s = Array[{# + 2, #} &, 8], r}, r = PolygonalNumber@ Range@ Total@ Flatten@ s; Map[Function[{a, b}, {First@ #, Set[r, Drop[Last@ #, b]]} &@ TakeDrop[r, a]] @@ # &, s][[All, 1]] // Flatten] (* _Michael De Vlieger_, Sep 25 2017 *) %Y A292610 Cf. A000217, A222716, A292611. %K A292610 nonn %O A292610 1,2 %A A292610 _Seiichi Manyama_, Sep 20 2017