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 A145237 #3 Mar 31 2012 12:35:07 %S A145237 1,4,24,216,2952,61488,1957392,95392296,7125411888,816458567400, %T A145237 143601085430064,38787148664334000,16094818374887017440, %U A145237 10263152688155204724288,10059484565080507620249504 %N A145237 1/3 of the number of 3-colorings of an n X n array symmetric about main diagonal. %K A145237 nonn %O A145237 1,2 %A A145237 _R. H. Hardin_, Oct 05 2008