A051758 Consider problem of placing A051755(n) queens on an n X n board so that each queen attacks precisely 2 others. Sequence gives number of solutions up to square symmetry.

1, 4, 2, 1, 1, 5, 2, 15

Offset

2,2

Links

Table of n, a(n) for n=2..9.

Crossrefs

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

Sequence in context: A152145 A288251 A024553 * A051568 A016509 A332630

Adjacent sequences: A051755 A051756 A051757 * A051759 A051760 A051761

Keyword

nonn,nice,more

Author

Robert Trent (trentrd(AT)hotmail.com), Aug 23 2000

Extensions

a(9) from Sean A. Irvine, Oct 05 2021

Status

approved