

A002566


Number of 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 M4130 N1713)


1



0, 6, 20, 12, 70, 960, 22, 352, 10, 216, 4814
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OFFSET

1,2


COMMENTS

Differs from A002564 and A002568 in that each queen is attacking at least one other queen.
M. A. SainteLaguë paper has "a(6)=900?".
In other words, the number of minimum total dominating sets in the n X n queen graph.  Eric W. Weisstein, Apr 19 2018


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. SainteLaguë, Les Réseaux (ou Graphes), Mémorial des Sciences Mathématiques, Fasc. 18, GauthierVillars, Paris, 1923, 64 pages. See p. 49.
M. A. SainteLaguë, Les Réseaux (ou Graphes), Mémorial des Sciences Mathématiques, Fasc. 18, GauthierVillars, Paris, 1923, 64 pages. See p. 49. [Incomplete annotated scan of title page and pages 1851]
Eric Weisstein's World of Mathematics, Queen Graph
Eric Weisstein's World of Mathematics, Total Dominating Set


CROSSREFS

Cf. A002565 (number of ways up to isomorphism).
Sequence in context: A281936 A075251 A090590 * A087998 A096823 A321328
Adjacent sequences: A002563 A002564 A002565 * A002567 A002568 A002569


KEYWORD

nonn,hard,more


AUTHOR

N. J. A. Sloane


EXTENSIONS

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


STATUS

approved



