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A145955
Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.
0
1, 1, 1, 3, 9, 23, 125, 821, 6239, 71403, 1048093, 19913069, 517074745, 17642361171, 795865550951, 47901047706833, 3815017258032049, 403246928224172293, 56605968541991726917, 10536114891916229568297, 2602764408693859006627701
OFFSET
1,4
EXAMPLE
Maximal 8 X 8 example
.0.0.0.0.0.0.1.0
.0.0.0.0.0.0.1.1
.0.0.0.1.1.0.0.1
.0.0.1.0.1.1.0.0
.0.0.1.1.0.0.1.0
.0.0.0.1.0.0.1.1
.1.1.0.0.1.1.0.1
.0.1.1.0.0.1.1.0
CROSSREFS
Sequence in context: A116659 A147508 A146472 * A129834 A376407 A029488
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2008
STATUS
approved