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A140954
Half the number of n X n binary matrices, symmetric under vertical reflection, having equal row sums.
1
1, 2, 10, 35, 1126, 7592, 1697508, 22458249, 36000614026, 941605438142, 11035829403860196, 572800408273738658, 49759074151291691916640, 5136409738603278958315040, 3340664790391139471267200338312
OFFSET
1,2
LINKS
R. H. Hardin, Jul 28 2008, Table of n, a(n) for n = 1..25
CROSSREFS
Sequence in context: A146983 A327075 A135963 * A309889 A155894 A317454
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 28 2008
STATUS
approved