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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 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

CROSSREFS

Sequence in context: A173945 A111846 A102922 * A197356 A072445 A000841

Adjacent sequences:  A139685 A139686 A139687 * A139689 A139690 A139691

KEYWORD

nonn

AUTHOR

R. H. Hardin (rhhardin(AT)att.net), Jun 13 2008

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Last modified February 17 11:46 EST 2012. Contains 206011 sequences.