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 A143875 #7 Oct 21 2014 03:41:10 %S A143875 1,2,11,155,3280,124511,7623993,795923016,140176308483,42642616703815 %N A143875 Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard. %Y A143875 Cf. A143870, A143881, A143886. %Y A143875 Cf. A143876, A143877, A143878, A143879, A143880. %K A143875 nonn,more,hard %O A143875 0,2 %A A143875 _R. H. Hardin_, Sep 04 2008