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Number of ways to place n nonattacking composite pieces queen + leaper[3,4] on an n X n chessboard.
1

%I #6 Sep 12 2015 11:00:25

%S 1,0,0,2,2,4,28,0,20,52,280,1192,5520,20196,115936,701836,4174032,

%T 27261284,193428616,1445733328,11133210948

%N Number of ways to place n nonattacking composite pieces queen + leaper[3,4] on an n X n chessboard.

%C a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+3)-p(i)|<>4 AND |p(j+4)-p(j)|<>3 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+3<=n, j+4<=n, m+k<=n

%H 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 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a>

%Y Cf. A051223, A189865, A189868, A189568

%K nonn,hard

%O 1,4

%A _Vaclav Kotesovec_, Apr 29 2011