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A139688
Half the number of n X n binary matrices with row sum i equal to column sum i, i in 1..n.
0
1, 4, 40, 1216, 123776, 44030464, 56185705472, 261929007759360, 4520504755804536832
OFFSET
1,2
CROSSREFS
Sequence in context: A290000 A363423 A102922 * A197356 A292416 A304985
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 13 2008
STATUS
approved