

A032522


Number of point symmetric solutions to nonattacking queens problem on n X n board.
(Formerly M0330 N0125)


7



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
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OFFSET

1,4


REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. J. Walker, An enumerative technique for a class of combinatorial problems, pp. 9194 of Proc. Sympos. Applied Math., vol. 10, Amer. Math. Soc., 1960.


LINKS

W. Schubert, Table of n, a(n) for n = 1..40
Tricia M. Brown, Kaleidoscopes, Chessboards, and Symmetry, Journal of Humanistic Mathematics, Volume 6 Issue 1 ( January 2016), pages 110126.
Gheorghe Coserea, Solutions for n=10.
Gheorghe Coserea, Solutions for n=11.
Gheorghe Coserea, MiniZinc model for generating solutions.
W. Schubert, NQueens page
M. Szabo, Nonattacking Queens Problem Page


CROSSREFS

Cf. A002562, A033148, A037224, A037223.
Sequence in context: A221590 A137778 A000017 * A077964 A077968 A123958
Adjacent sequences: A032519 A032520 A032521 * A032523 A032524 A032525


KEYWORD

nonn,nice,hard


AUTHOR

Miklos SZABO (mike(AT)ludens.elte.hu)


EXTENSIONS

More terms for n = 33..36 from W. Schubert, Jul 31 2009


STATUS

approved



