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A189842
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Number of ways to place n nonattacking composite pieces rook + rider[6,6] on an n X n chessboard.
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1
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1, 2, 6, 24, 120, 720, 4800, 34752, 280512, 2528256, 25282560, 278323200, 3242649600, 40330371072, 536528954880, 7633092132864
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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(j+6k)-p(j)|<>6k for all j>=1, k>=1, j+6k<=n
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LINKS
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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STATUS
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approved
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