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A145937
Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 2X2 elbow 1,1 1,2 2,1 in any orientation.
0
1, 1, 1, 1, 5, 5, 19, 19, 161, 161, 4227, 4227, 156459, 156459, 12465353, 12465353, 2072728127, 2072728127, 654619864141, 654619864141, 416229285287827, 416229285287827, 526917547596105835, 526917547596105835
OFFSET
1,5
FORMULA
Maximal 8 X 8 example
.1.1.0.0.0.0.1.1
.1.0.1.0.0.1.0.1
.0.1.1.0.0.1.1.0
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.0.1.1.0.0.1.1.0
.1.0.1.0.0.1.0.1
.1.1.0.0.0.0.1.1
CROSSREFS
Sequence in context: A147101 A147141 A146146 * A246983 A305514 A039914
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2008
STATUS
approved