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A051906
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Number of ways of placing n nonattacking toroidal queens on an n x n chess board.
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5
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1, 0, 0, 0, 10, 0, 28, 0, 0, 0, 88, 0, 4524, 0, 0, 0, 140692, 0, 820496, 0, 0, 0, 128850048, 0, 1957725000, 0, 0, 0, 605917055356
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| The sequence is given to n=23 in the reference. Further terms were calculated by the submitter, Dec 17, 1999 and Jan 11, 2001.
a(n) is divisible by n.
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REFERENCES
| M. R. Engelhardt, A group-based search for solutions of the n-queens problem, Discr. Math., 307 (2007), 2535-2551.
I. Rivin, I.Vardi and P.Zimmermann, The n-queens problem, Amer. Math. Monthly, 101 (1994), 629-639
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CROSSREFS
| See A007705, which is the main entry for this sequence.
Sequence in context: A107781 A107772 A087474 * A171809 A167302 A084033
Adjacent sequences: A051903 A051904 A051905 * A051907 A051908 A051909
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KEYWORD
| nonn,nice,hard
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AUTHOR
| Matthias Engelhardt (Matthias.R.Engelhardt(AT)web.de), Dec 17 1999
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