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A057629 Number of alternating sign 2n X 2n matrices invariant under flips in both diagonals. 0
2, 8, 52, 568, 10436, 323144, 16866856 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

LINKS

D. P. Robbins, Symmetry classes of alternating sign matrices, arXiv:math.CO/0008045

CROSSREFS

Sequence in context: A151879 A191552 A154828 * A191507 A191602 A145157

Adjacent sequences:  A057626 A057627 A057628 * A057630 A057631 A057632

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Oct 10 2000

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Last modified February 15 12:05 EST 2012. Contains 205782 sequences.