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A145950
Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected in a 3X2 elbow 1,1 1,2 1,3 2,3 in any orientation.
0
1, 1, 1, 9, 31, 205, 1307, 12227, 171281, 3266929, 85166971, 3120438693, 149314103237, 10059913232521, 894685834014771
OFFSET
1,4
EXAMPLE
Maximal 8 X 8 example
.0.0.0.1.1.0.1.1
.1.0.0.1.0.1.0.1
.1.0.0.1.0.1.0.1
.1.1.0.0.1.1.0.0
.0.0.1.1.0.0.1.1
.1.0.1.0.1.0.0.1
.1.0.1.0.1.0.0.1
.1.1.0.1.1.0.0.0
CROSSREFS
Sequence in context: A140323 A160653 A189436 * A177743 A266710 A159279
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2008
STATUS
approved