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A032522 Number of point symmetric solutions to non-attacking 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 (list; graph; refs; listen; history; text; internal format)
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. 91-94 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 110-126.

Gheorghe Coserea, Solutions for n=10.

Gheorghe Coserea, Solutions for n=11.

Gheorghe Coserea, MiniZinc model for generating solutions.

W. Schubert, N-Queens page

M. Szabo, Non-attacking 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

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Last modified December 15 13:23 EST 2018. Contains 318149 sequences. (Running on oeis4.)