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, 2, 3, 13, 40, 313, 1833, 27784, 312227, 9039597, 194485968, 10791499905, 444739929613, 47257907376576, 3730171679762583, 759195182636849001, 114775951820515671520, 44741688449064266073777

Offset

0,2

Links

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

Crossrefs

Sequence in context: A347537 A289549 A259261 * A235615 A117528 A264042

Adjacent sequences: A141508 A141509 A141510 * A141512 A141513 A141514

Keyword

nonn

Author

R. H. Hardin, Aug 10 2008

Status

approved