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A189861
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Number of ways to place n nonattacking composite pieces rook + rider[4,5] on an n X n chessboard.
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1
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1, 2, 6, 24, 120, 552, 2826, 17080, 117816, 943250, 7369128, 63533572, 603300392, 6280101222, 71927971040, 836503868762
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OFFSET
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1,2
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COMMENTS
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a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>4k for all i>=1, j>=1, k>=1, i+4k<=n, j+5k<=n
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LINKS
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Table of n, a(n) for n=1..16.
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. A000170, A189852, A189856, A189859
Sequence in context: A178848 A173845 A072856 * A189570 A179340 A179342
Adjacent sequences: A189858 A189859 A189860 * A189862 A189863 A189864
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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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