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A146037
Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 3X3 el 1,1 1,2 1,3 2,3 3,3 in any orientation.
0
1, 1, 1, 3, 7, 19, 89, 399, 1939, 11793, 102715, 985113, 13989079, 211198639, 4331591655, 98297746517, 2965968725989, 100683520176799
OFFSET
1,4
EXAMPLE
Maximal 8 X 8 example
.0.0.0.0.0.1.1.1
.1.1.1.0.0.0.0.1
.1.0.0.1.1.1.0.1
.1.0.1.0.0.1.0.0
.0.0.1.0.0.1.0.1
.1.0.1.1.1.0.0.1
.1.0.0.0.0.1.1.1
.1.1.1.0.0.0.0.0
CROSSREFS
Sequence in context: A322852 A243583 A215487 * A172514 A128024 A245723
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 26 2008
STATUS
approved