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A189865
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Number of ways to place n nonattacking composite pieces queen + leaper[1,4] on an n X n chessboard.
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3
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1, 0, 0, 2, 10, 0, 0, 4, 32, 76, 196, 632, 3368, 12532, 79788, 468286, 2815088, 18287968, 126620984, 938037664, 7232141830, 59774887344
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OFFSET
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1,4
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COMMENTS
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In fairy chess the leaper [1,4] is called a giraffe.
a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+1)-p(i)|<>4 AND |p(j+4)-p(j)|<>1 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+1<=n, j+4<=n, m+k<=n
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LINKS
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Table of n, a(n) for n=1..22.
V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)
Wikipedia, Fairy chess piece
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CROSSREFS
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Cf. A051223, A189864, A189563
Sequence in context: A189875 A189866 A189874 * A189880 A189871 A096877
Adjacent sequences: A189862 A189863 A189864 * A189866 A189867 A189868
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KEYWORD
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nonn,hard
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AUTHOR
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Vaclav Kotesovec, Apr 29 2011
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STATUS
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approved
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