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 A143876 #5 Oct 20 2014 18:31:42 %S A143876 1,2,3,27,26,1119,921,122658,74887,43743593,18775998,43803694319, %T A143876 14699916393,143879089856822,34113001129873 %N A143876 Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under horizontal reflection. %K A143876 nonn,more,hard %O A143876 0,2 %A A143876 _R. H. Hardin_, Sep 04 2008