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A140453 Half the number of n X n binary matrices, symmetric under horizontal and vertical reflection, having equal row sums. 1
1, 1, 2, 3, 10, 28, 164, 905, 9826, 103126, 2031252, 43437282, 1622278624, 66141208960, 4579408029576, 385335180349569, 51207103076632066, 8212830157184175946, 2052124795850957537060, 683805150345009276656138 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

R. H. Hardin, Jul 28 2008, Table of n, a(n) for n = 1..25

CROSSREFS

Sequence in context: A007029 A298083 A099435 * A037169 A058953 A160909

Adjacent sequences:  A140450 A140451 A140452 * A140454 A140455 A140456

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 28 2008

STATUS

approved

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Last modified September 22 03:15 EDT 2018. Contains 315267 sequences. (Running on oeis4.)