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 A143885 #5 Oct 20 2014 18:34:37 %S A143885 1,2,3,15,52,383,2273,28764,295391,6544311,116636234 %N A143885 Number of ways of placing kings with no more than 3 mutual attacks on an n X n chessboard symmetric under 180 degree rotation. %K A143885 nonn,more,hard %O A143885 0,2 %A A143885 _R. H. Hardin_, Sep 04 2008