A002568 - OEIS

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A002568

Number of different ways one can attack all squares on an n X n chessboard with the smallest number of queens needed.
(Formerly M3200 N1294)

1, 4, 1, 16, 16, 120, 8, 728, 92, 8, 2, 840 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	REFERENCES	`M. A. Sainte-Lagu\"{e}, Les R\'{e}seaux (ou Graphes)}, M\'{e}morial des Sciences Math\'{e}matiques, Fasc. 18, Gauthier-Villars, Paris, 1926, p. 49.` `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).`
	EXAMPLE	`a(5) = 16 because it is impossible to attack all squares with 2 queens but with 3 queens you can do it in 16 different ways (with mirroring and rotation).`
	CROSSREFS	`Sequence in context: A075499 A099394 A059991 * A111661 A072651 A093035` `Adjacent sequences: A002565 A002566 A002567 * A002569 A002570 A002571`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`
	EXTENSIONS	`a(9)-a(12) from Johan Sarnbratt (johan.sarnbratt(AT)gmail.com), Mar 28 2008`

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Last modified February 16 09:27 EST 2012. Contains 205904 sequences.