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A140988 Half the number of symmetric n X n binary matrices having equal row sums. 0
1, 2, 5, 20, 139, 1777, 42295, 1888140, 158903233, 25355226287, 7707419775769 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
CROSSREFS
Sequence in context: A297630 A297629 A118181 * A136650 A229662 A111885
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 28 2008
STATUS
approved

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Last modified February 27 19:16 EST 2024. Contains 370378 sequences. (Running on oeis4.)