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 A066972 #5 Jun 01 2010 03:00:00 %S A066972 3,12,42,144,728,2688,10080,39312,127008,423360,2419200,6773760, %T A066972 32140800 %N A066972 Duplicate of A067819. %K A066972 dead %O A066972 1,1