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A137279
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Number of ways of placing (m+1)/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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The chessboard is an n X n standard chessboard whose left and right edges are twisted connected.
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REFERENCES
| J. Bell and B. Stevens, Results for the n-queens problem on the Mobius board, to appear in the Australasian Journal of Combinatorics, 2008.
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EXAMPLE
| 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
| Cf. A000170, A007705, A002562, A053994, A061989, A061990.
Sequence in context: A007216 A057378 A002979 * A167350 A156457 A058348
Adjacent sequences: A137276 A137277 A137278 * A137280 A137281 A137282
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KEYWORD
| nonn
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AUTHOR
| brett stevens (brett(AT)math.carleton.ca), Mar 13 2008
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