A137279 Number of ways of placing ceiling(n/2) nonattacking queens on an n X n Mobius chessboard.

1, 4, 0, 16, 40, 192, 560, 3328, 11772, 63840, 259336, 1550976, 7169656, 42410256, 234044160, 1366190592

Offset: 1

Author

Brett Stevens (brett(AT)math.carleton.ca), Mar 13 2008

Keywords

• nonn
• more

Comments

The chessboard is an n X n standard chessboard whose left and right edges are twisted connected.

Examples

			a(4)=16 because any queen attacks all but two other squares and every solution is counted twice by enumerating all such placements.
		

Links

• J. Bell and B. Stevens, Results for the n-queens problem on the Mobius board, Australasian Journal of Combinatorics, vol.42, p.21 (2008).

Crossrefs

Cf. A000170, A007705, A002562, A053994, A061989, A061990.