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A146156
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either as two by three or three by two blocks.
0
1, 1, 1, 1, 1, 1, 2, 4, 7, 11, 20, 47, 126, 349, 1026, 3169, 10962, 42335, 178967, 817710, 4108982, 22332287, 134485764, 875416554, 6255533128, 48551931040, 415466055841, 3858971189964, 39521400790374, 437870905678969
OFFSET
1,7
EXAMPLE
Maximal 8 X 8 example
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.1.1.1.0.0.1.1.1
.1.1.1.0.0.1.1.1
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
CROSSREFS
Sequence in context: A018173 A288380 A369581 * A304916 A024927 A018077
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 27 2008
STATUS
approved