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A002565 Number of non-isomorphic ways to attack all squares on an n X n chessboard using the smallest possible number of queens with each queen attacking at least one other.
(Formerly M1313 N0502)
1
0, 2, 5, 3, 15, 150, 5, 56, 3, 39, 681 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Differs from A002563 and A002567 in that each queen is attacking at least one other queen. - Sean A. Irvine, Apr 05 2014

The Sainte-Laguë paper has "a(6)=140?". - Sean A. Irvine, Apr 05 2014

REFERENCES

W. Ahrens, Mathematische Unterhaltungen und Spiele, second edition (1910), Vol. 1, p. 301.

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).

LINKS

Table of n, a(n) for n=1..11.

M. A. Sainte-Laguë, Les Réseaux (ou Graphes), Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 49.

M. A. Sainte-Laguë, Les Réseaux (ou Graphes), Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 49. [Incomplete annotated scan of title page and pages 18-51]

CROSSREFS

Cf. A002566 (all solutions for attacking queens). - Sean A. Irvine, Apr 05 2014

Sequence in context: A243066 A181921 A282575 * A063703 A109619 A248576

Adjacent sequences:  A002562 A002563 A002564 * A002566 A002567 A002568

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(6) corrected and a(9)-a(11) from Sean A. Irvine, Apr 05 2014

Better name from Sean A. Irvine, Apr 05 2014

STATUS

approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)