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 A189256 #19 Feb 08 2023 09:08:19 %S A189256 1,2,6,24,120,672,4128,28992,231936,2088960,20434944,221871360, %T A189256 2645370624,34344038400,482103767040,7269498483456,117240911729664, %U A189256 2013265377314688,36665783917283328,705762463906133760,14313891805008665856 %N A189256 Number of permutations p of 1,2,...,n satisfying |p(i+5)-p(i)|<>5 for all 1<=i<=n-5. %C A189256 a(n) is also number of ways to place n nonattacking pieces rook + leaper[5,5] on an n X n chessboard. %H A189256 Vaclav Kotesovec, <a href="/A189256/b189256.txt">Table of n, a(n) for n = 1..26</a> %H A189256 Vaclav Kotesovec, <a href="http://www.kotesovec.cz/books/kotesovec_non_attacking_chess_pieces_2013_6ed.pdf">Non-attacking chess pieces</a>, Sixth edition, p. 633, Feb 02 2013. %H A189256 Vaclav Kotesovec, <a href="/A189256/a189256.txt">Mathematica program for this sequence</a> %H A189256 Roberto Tauraso, <a href="http://www.emis.de/journals/INTEGERS/papers/g11/g11.Abstract.html">The Dinner Table Problem: The Rectangular Case</a>, INTEGERS: Electronic Journal of Combinatorial Number Theory, Vol. 6 (2006), #A11. %F A189256 Asymptotic (R. Tauraso 2006, quadratic term V. Kotesovec 2011): a(n)/n! ~ (1 + 16/n + 110/n^2)/e^2. %Y A189256 Cf. A002464, A110128, A117574, A189255. %Y A189256 Column k=5 of A333706. %K A189256 nonn,hard %O A189256 1,2 %A A189256 _Vaclav Kotesovec_, Apr 19 2011 %E A189256 Terms a(25)-a(26) from _Vaclav Kotesovec_, Apr 20 2012