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 A137172 #4 Mar 30 2012 18:51:57 %S A137172 0,1,2,3,4,6,10,12,16,20,28,36,56,64,72,120,136,240,256,272,496,528, %T A137172 992,1024,1056,2016,2080,4032,4096,4160,8128,8256,16256,16384,16512, %U A137172 32640,32896,65280,65536,65792,130816,131328,261632,262144,262656,523776,524800,1047552 %N A137172 Numbers in the array A137171. %C A137172 Union of the first three rows of the array in A137171, sorted. %K A137172 nonn %O A137172 1,3 %A A137172 _Paul Curtz_, May 11 2008 %E A137172 Definition corrected and more terms added by _R. J. Mathar_, Jul 29 2009