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 A189867 #6 Sep 12 2015 11:00:25 %S A189867 1,0,0,2,10,0,0,0,0,48,152,472,2696,12320,74436,429620,2515116, %T A189867 16122496,113016608,843492920,6575649316,54694203188 %N A189867 Number of ways to place n nonattacking composite pieces queen + leaper[2,3] on an n X n chessboard. %C A189867 In fairy chess the leaper [2,3] is called a zebra. %C A189867 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2)-p(i)|<>3 AND |p(j+3)-p(j)|<>2 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2<=n, j+3<=n, m+k<=n %H A189867 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 A189867 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189867 Cf. A051223, A189864, A189565 %K A189867 nonn,hard %O A189867 1,4 %A A189867 _Vaclav Kotesovec_, Apr 29 2011