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

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

%S 1,2,6,20,80,384,2112,12992,94272,716800,6141440,58451568,596647568,

%T 6555879072,77766001056,981202169600

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

%C a(n) is also number of permutations p of 1,2,...,n satisfying |p(j+3k)-p(j)|<>3k for all j>=1, k>=1, j+3k<=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. A117574, A000170, A189838

%K nonn,hard

%O 1,2

%A _Vaclav Kotesovec_, Apr 29 2011