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 A109826 #3 Mar 30 2012 17:26:17
%S A109826 3,4,8,9,10,15,17,20,21,22,35,38,39,42,44,46,48,49,53,59,61,62,68,69,
%T A109826 71,73,74,88,92,93,94,95,98,103,105,106,108,110,111,114,115,125,127,
%U A109826 134,139,143,145,146,148,150,152,158,159,161,164,169,171,174,178,183,189
%N A109826 Final terms of groups in the partition of the sequence of natural numbers A109411.
%t A109826 s={3};a=4;Do[Do[If[Plus@@Last/@FactorInteger[(a+x)(x-a+1)/2]==2, a=x+1;AppendTo[s, x];Break[]], {x, a, 20000}], {k, 1, 100}];A109826=s
%Y A109826 Cf. A109411, A109825.
%K A109826 nonn
%O A109826 1,1
%A A109826 _Zak Seidov_, Jul 03 2005