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 A189872 #6 Sep 12 2015 11:00:25 %S A189872 1,0,0,2,10,4,12,32,96,144,576,2280,11988,47128,232756,1290772, %T A189872 7383588,46039788,311958088,2263575696,16975534432 %N A189872 Number of ways to place n nonattacking composite pieces queen + leaper[4,5] on an n X n chessboard. %C A189872 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4)-p(i)|<>5 AND |p(j+5)-p(j)|<>4 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+4<=n, j+5<=n, m+k<=n %H A189872 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 A189872 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189872 Cf. A051223, A189866, A189869, A189871, A189570 %K A189872 nonn,hard %O A189872 1,4 %A A189872 _Vaclav Kotesovec_, Apr 29 2011