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 A189866 #6 Sep 12 2015 11:00:25 %S A189866 1,0,0,2,10,0,0,0,40,52,160,500,2656,11540,67776,415716,2610520, %T A189866 17450592,124903880,944965832,7292031780 %N A189866 Number of ways to place n nonattacking composite pieces queen + leaper[1,5] on an n X n chessboard. %C A189866 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+1)-p(i)|<>5 AND |p(j+5)-p(j)|<>1 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+1<=n, j+5<=n, m+k<=n %H A189866 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 A189866 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189866 Cf. A051223, A189864, A189865, A189564 %K A189866 nonn,hard %O A189866 1,4 %A A189866 _Vaclav Kotesovec_, Apr 29 2011