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.

0, 2, 5, 3, 15, 150, 5, 56, 3, 39, 681

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• more

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

• 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

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