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 A051567 Consider problem of placing N queens on an n X n board so that each queen attacks precisely k others. Here k=1 and sequence gives number of inequivalent solutions when N is equal to the upper bound 2*floor(2n/3). 14
 0, 5, 0, 2, 149, 49, 1, 12897, 2238 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,2 COMMENTS a(n) = 0 if N does not achieve 2*floor(2n/3). REFERENCES M. Gardner, The Last Recreations, Springer, 1997, p. 282. M. Gardner, The Colossal Book of Mathematics, 2001, p. 209. LINKS Martin Gardner, The Last Recreations, 1997 Vaclav Kotesovec, The unique solution for chessboard 9 X 9 Manfred Scheucher, C Code CROSSREFS Cf. A051568-A051571, A051754-A051759, A019654. The number of solutions when N takes its maximal value is A051757. Sequence in context: A190913 A019106 A051566 * A261219 A085850 A176867 Adjacent sequences:  A051564 A051565 A051566 * A051568 A051569 A051570 KEYWORD nonn,more,nice AUTHOR EXTENSIONS Description corrected by and one more term from Jud McCranie, Aug 25 2001 STATUS approved

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Last modified December 12 01:57 EST 2019. Contains 329948 sequences. (Running on oeis4.)