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A146151
Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation.
0
1, 1, 1, 3, 9, 27, 119, 633, 3943, 30791, 332473, 4676705, 79725173, 1817184081, 50545874411, 1811092006865
OFFSET
1,4
EXAMPLE
Maximal 8 X 8 example
.0.1.1.0.0.1.1.0
.1.1.0.0.0.0.1.1
.1.0.0.1.0.0.0.1
.0.0.1.1.0.1.1.0
.0.1.1.0.1.1.0.0
.1.0.0.0.1.0.0.1
.1.1.0.0.0.0.1.1
.0.1.1.0.0.1.1.0
CROSSREFS
Sequence in context: A230951 A121746 A323927 * A306681 A254334 A375093
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 27 2008
STATUS
approved