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 A189861 #6 Sep 12 2015 11:00:25 %S A189861 1,2,6,24,120,552,2826,17080,117816,943250,7369128,63533572,603300392, %T A189861 6280101222,71927971040,836503868762 %N A189861 Number of ways to place n nonattacking composite pieces rook + rider[4,5] on an n X n chessboard. %C A189861 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>4k for all i>=1, j>=1, k>=1, i+4k<=n, j+5k<=n %H A189861 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Number of ways of placing non-attacking queens, kings, bishops and knights</a> (in English and Czech) %H A189861 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189861 Cf. A000170, A189852, A189856, A189859 %K A189861 nonn,hard %O A189861 1,2 %A A189861 _Vaclav Kotesovec_, Apr 29 2011