

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




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

Table of n, a(n) for n=3..11.
Martin Gardner, The Last Recreations, 1997
Vaclav Kotesovec, The unique solution for chessboard 9 X 9
Manfred Scheucher, C Code


CROSSREFS

Cf. A051568A051571, A051754A051759, 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

N. J. A. Sloane


EXTENSIONS

Description corrected by and one more term from Jud McCranie, Aug 25 2001


STATUS

approved



