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 A189876 #6 Sep 12 2015 11:00:25 %S A189876 1,0,0,2,10,0,0,0,0,16,60,40,304,620,2512,8734,28410,94312,345824, %T A189876 1391072,5759566,25227796,121663032,635977968 %N A189876 Number of ways to place n nonattacking composite pieces queen + rider[2,3] on an n X n chessboard. %C A189876 (in fairy chess the rider [2,3] is called a Zebrarider) %C A189876 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2k)-p(i)|<>3k AND |p(j+3k)-p(j)|<>2k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2k<=n, j+3k<=n, m+k<=n %H A189876 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 A189876 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189876 Cf. A102388, A189873, A189854 %K A189876 nonn,hard %O A189876 1,4 %A A189876 _Vaclav Kotesovec_, Apr 29 2011