A051569 Consider the problem of placing N = A051756(n) queens on an n X n board so that each queen attacks precisely 3 others; a(n) gives the number of inequivalent solutions.

1, 2, 4, 31, 304, 2, 9, 755, 39302

Offset

2,2

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=2..10.

Crossrefs

Cf. A051567-A051571, A051754-A051759, A019654.

Sequence in context: A339603 A188113 A259115 * A087186 A051759 A051570

Adjacent sequences: A051566 A051567 A051568 * A051570 A051571 A051572

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

I am not certain this description is correct, nor how rigorous the results are. Probably this is an incorrect version of A051759.

Status

approved