|
| |
|
|
A146303
|
|
Number of distinct ways to place queens (even fewer than n) on a n*n chessboard so that no queen is attacking another and that it is not possible to add another queen.
|
|
1
| |
|
|
1, 4, 9, 18, 58, 348, 1862, 10188, 57600, 376692, 2640422
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
REFERENCES
| S. W. Golomb and L. D. Baumert, Backtrack Programming, Journal of the ACM, 4 (2001), 516-524.
|
|
|
EXAMPLE
| For n=2, the a(n) = 4 solutions are to place a single queen in each of the squares of the chessboard. For n=3, there is a single one-queen solution (placing the queen in b2) and eight two-queen solutions, but no three-queen solution (see A000170).
|
|
|
CROSSREFS
| Cf. A000170, A146304
Sequence in context: A074896 A015713 A049198 * A203205 A147977 A045278
Adjacent sequences: A146300 A146301 A146302 * A146304 A146305 A146306
|
|
|
KEYWORD
| hard,nonn
|
|
|
AUTHOR
| Paolo Bonzini (bonzini(AT)gnu.org), Oct 29 2008
|
| |
|
|
