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 A189881 #6 Sep 12 2015 11:00:25 %S A189881 1,0,0,2,10,4,12,32,96,144,528,1712,7472,24500,103536,486020,2218808, %T A189881 11113020,59242576,342584556,1981826412 %N A189881 Number of ways to place n nonattacking composite pieces queen + rider[4,5] on an n X n chessboard. %C A189881 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 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+4k<=n, j+5k<=n, m+k<=n %H A189881 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 A189881 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189881 Cf. A102388, A189875, A189878, A189880, A189861 %K A189881 nonn,hard %O A189881 1,4 %A A189881 _Vaclav Kotesovec_, Apr 29 2011