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 A189567 #9 Mar 19 2017 16:22:35 %S A189567 1,1,2,6,24,120,392,1810,10400,72228,589674,5196870,52398658, %T A189567 588036216,7274466172,98024173852,1427556373892 %N A189567 Number of permutations p of 1,2,...,n satisfying |p(i+2)-p(i)|<>5 and |p(j+5)-p(j)|<>2 for all i=1..n-2, j=1..n-5. %C A189567 a(n) is also the number of ways to place n nonattacking pieces rook + leaper[2,5] on an n X n chessboard. %H A189567 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) %F A189567 Asymptotic: a(n)/n! ~ 1/e^4. %Y A189567 Cf. A137774, A189358, A189563, A189564, A189565, A189566. %K A189567 nonn,more,hard %O A189567 0,3 %A A189567 _Vaclav Kotesovec_, Apr 23 2011