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Search: id:A032522
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| A032522 |
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Number of symmetric solutions to non-attacking queens problem on n X n board.
(Formerly M0330 N0125)
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+0
6
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| 1, 0, 0, 2, 2, 4, 8, 4, 16, 12, 48, 80, 136, 420, 1240, 3000, 8152, 18104, 44184, 144620, 375664, 1250692, 3581240, 11675080, 34132592, 115718268, 320403024, 1250901440, 3600075088, 14589438024, 43266334696, 181254386312
(list; graph; listen)
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OFFSET
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1,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
R. J. Walker, An enumerative technique for a class of combinatorial problems, pp. 91-94 of Proc. Sympos. Applied Math., vol. 10, Amer. Math. Soc., 1960.
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LINKS
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W. Schubert, Table of n, a(n) for n = 1..36
M. Szabo, Non-attacking Queens Problem Page
W. Schubert, N-Queens page
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CROSSREFS
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Cf. A002562, A033148, A037224, A037223.
Sequence in context: A116694 A137778 A000017 this_sequence A077964 A077968 A123958
Adjacent sequences: A032519 A032520 A032521 this_sequence A032523 A032524 A032525
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KEYWORD
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nonn,nice,hard
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AUTHOR
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Miklos SZABO (mike(AT)ludens.elte.hu)
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EXTENSIONS
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More terms for n = 33..36 from W. Schubert (wschubnq(AT)gmx.de), Jul 31 2009
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