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 A189847 #6 Sep 12 2015 11:00:25 %S A189847 1,2,6,24,120,696,4572,34260,290328,2751480,28426056,318900264, %T A189847 3874868280,50813711808,716309557440,10721493269568 %N A189847 Number of ways to place n nonattacking composite pieces rook + semi-rider[5,5] on an n X n chessboard. %C A189847 a(n) is also number of permutations p of 1,2,...,n satisfying p(j+5k)-p(j)<>5k for all j>=1, k>=1, j+5k<=n %C A189847 For information about semi-pieces see semi-bishop (A187235) and semi-queen (A099152). %H A189847 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 A189847 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a> %Y A189847 Cf. A189284, A099152, A189843, A189844, A189846, A189841, A187235 %K A189847 nonn,hard %O A189847 1,2 %A A189847 _Vaclav Kotesovec_, Apr 29 2011