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A146009
Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 3X3 tee 1,1 1,2 1,3 2,2 3,2 in any orientation.
0
1, 1, 1, 1, 3, 9, 22, 75, 380, 2417, 17011, 150387, 1725197, 24767029, 439881987, 9753623996, 269467512241, 9272282447537, 399403152426578, 21537582386961680, 1447800106086744192, 121198502960515093107
OFFSET
1,5
EXAMPLE
Maximal 8 X 8 example
.0.0.1.1.1.0.0.0
.0.0.0.1.0.0.0.0
.1.0.0.1.0.0.0.0
.1.1.1.0.0.0.0.1
.1.0.0.0.0.1.1.1
.0.0.0.0.1.0.0.1
.0.0.0.0.1.0.0.0
.0.0.0.1.1.1.0.0
CROSSREFS
Sequence in context: A296582 A203454 A197666 * A326007 A272559 A270991
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 26 2008
STATUS
approved