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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
OFFSET
0,2
LINKS
CROSSREFS
Sequence in context: A347537 A289549 A259261 * A235615 A117528 A264042
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 10 2008
STATUS
approved