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 A244284 #6 Sep 12 2015 11:00:29 %S A244284 1,6,84,1168,20502,525796,18939708,802444170,38934305898,2170312156170 %N A244284 Number of ways to place n nonattacking zebras on an n X n chessboard. %C A244284 Zebra is a (fairy chess) leaper [2,3]. %H A244284 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, p.363 %H A244284 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %F A244284 a(n) ~ n^(2*n)/n! * exp(-9/2). %Y A244284 Cf. A172137, A172138, A172139, A172140. %Y A244284 Cf. A201540, A201511, A201861, A201513. %K A244284 nonn,hard,more %O A244284 1,2 %A A244284 _Vaclav Kotesovec_, Jun 25 2014