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A140974 Number of binary n X n matrices symmetric about both diagonals with rows, considered as binary numbers, in nondecreasing order. 0
1, 2, 3, 4, 8, 16, 43, 136, 513, 2662, 15276, 134366, 1233504, 18634052, 281749759, 7363023774, 187712397424, 8557170854702, 375321111906249 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

CROSSREFS

Sequence in context: A224912 A162724 A244750 * A296109 A102276 A215897

Adjacent sequences:  A140971 A140972 A140973 * A140975 A140976 A140977

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 27 2008

STATUS

approved

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Last modified April 9 20:11 EDT 2020. Contains 333362 sequences. (Running on oeis4.)