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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; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..9.

CROSSREFS

Sequence in context: A173945 A111846 A102922 * A197356 A292416 A304985

Adjacent sequences:  A139685 A139686 A139687 * A139689 A139690 A139691

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 13 2008

STATUS

approved

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Last modified November 12 21:22 EST 2019. Contains 329079 sequences. (Running on oeis4.)