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 A031990 #10 Aug 04 2016 22:50:33 %S A031990 1,2,3,4,6,7,8,9,12,13,14,18,19,24,31,32,33,34,37,38,39,43,44,49,62, %T A031990 63,64,68,69,74,93,94,99,124,156,157,158,159,162,163,164,168,169,174, %U A031990 187,188,189,193,194,199,218,219,224,249,312,313 %N A031990 Duplicate of A023747. %K A031990 dead %O A031990 1,2