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A137279
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Number of ways of placing ceiling(n/2) nonattacking queens on an n X n Mobius chessboard.
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0
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1, 4, 0, 16, 40, 192, 560, 3328, 11772, 63840, 259336, 1550976, 7169656, 42410256, 234044160, 1366190592
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OFFSET
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1,2
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COMMENTS
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The chessboard is an n X n standard chessboard whose left and right edges are twisted connected.
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LINKS
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Table of n, a(n) for n=1..16.
J. Bell and B. Stevens, Results for the n-queens problem on the Mobius board, Australasian Journal of Combinatorics, vol.42, p.21 (2008).
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EXAMPLE
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a(4)=16 because any queen attacks all but two other squares and every solution is counted twice by enumerating all such placements.
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CROSSREFS
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Cf. A000170, A007705, A002562, A053994, A061989, A061990.
Sequence in context: A057378 A247120 A002979 * A233807 A302771 A167350
Adjacent sequences: A137276 A137277 A137278 * A137280 A137281 A137282
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KEYWORD
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nonn,more
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AUTHOR
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Brett Stevens (brett(AT)math.carleton.ca), Mar 13 2008
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STATUS
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approved
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