cp's OEIS Frontend

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.

A189877 Number of ways to place n nonattacking composite pieces queen + rider[2,4] on an n X n chessboard.

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%I A189877 #6 Sep 12 2015 11:00:25
%S A189877 1,0,0,2,0,0,0,0,0,4,56,172,680,1348,6576,34568,107624,413760,1697288,
%T A189877 8035558,37441416,192483420,1115143224
%N A189877 Number of ways to place n nonattacking composite pieces queen + rider[2,4] on an n X n chessboard.
%C A189877 a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2k)-p(i)|<>4k AND |p(j+4k)-p(j)|<>2k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2k<=n, j+4k<=n, m+k<=n
%H A189877 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 A189877 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a>
%Y A189877 Cf. A102388, A189874, A189876, A189855
%K A189877 nonn,hard
%O A189877 1,4
%A A189877 _Vaclav Kotesovec_, Apr 29 2011