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A189875
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Number of ways to place n nonattacking composite pieces queen + rider[1,5] on an n X n chessboard.
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3
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1, 0, 0, 2, 10, 0, 0, 0, 40, 52, 152, 260, 1192, 4144, 18408, 71552, 312936, 1498156, 7854672, 44923706, 213840604, 1156549592
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OFFSET
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1,4
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COMMENTS
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a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+k<=n, j+5k<=n, m+k<=n
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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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