

A137279


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


0



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

1,2


COMMENTS

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


LINKS



EXAMPLE

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


CROSSREFS



KEYWORD

nonn,more


AUTHOR

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


STATUS

approved



