A019654 Consider problem of placing N queens on an n X n board so that each queen attacks precisely k others. Here k=4 and sequence gives number of different solutions when N takes its maximal value.

0, 1, 1, 1, 3, 40, 655, 16573

Offset

3,5

Comments

I would also like to get the sequences that give the maximal value of N.

Maximal values given by A063724. - Sean A. Irvine, Mar 31 2019

Values for a(9) onwards currently unverified. - Sean A. Irvine, Apr 05 2019

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..10.

Sean A. Irvine, Solutions for n<=8

Eric Weisstein's World of Mathematics, Queens Problem [From Claudio (lordofchaos000(AT)hotmail.com), May 31 2010]

Crossrefs

Cf. A051567-A051571, A051754-A051759, A063724.

Sequence in context: A215196 A093376 A051571 * A361069 A327070 A156356

Adjacent sequences: A019651 A019652 A019653 * A019655 A019656 A019657

Keyword

nonn,nice,more

Author

N. J. A. Sloane, Oct 03 2002

Extensions

I am not certain this description is correct, nor how rigorous the results are.

a(4) and a(5) changed to 1 and irrelevant comment removed by Sean A. Irvine, Apr 02 2019

Status

approved