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A141511 Number of n X n binary matrices, symmetric about both diagonal and antidiagonal, with no more than 3 ones in any 2 X 2 subblock. 1
1, 2, 3, 13, 40, 313, 1833, 27784, 312227, 9039597, 194485968, 10791499905, 444739929613, 47257907376576, 3730171679762583, 759195182636849001, 114775951820515671520, 44741688449064266073777 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

R. H. Hardin, Table of n, a(n) for n = 0..24

CROSSREFS

Sequence in context: A100424 A289549 A259261 * A235615 A117528 A264042

Adjacent sequences:  A141508 A141509 A141510 * A141512 A141513 A141514

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 10 2008

STATUS

approved

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Last modified March 28 07:59 EDT 2020. Contains 333079 sequences. (Running on oeis4.)