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A146047
Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.
0
1, 1, 1, 1, 13, 19, 471, 1011, 17363, 51133, 4227773, 17426251, 4189737457, 23548416611, 8347118368027, 61971666176727, 58964882823496375, 583865226098623749, 1588500435723596374221, 21184137467738936180415
OFFSET
1,5
EXAMPLE
Maximal 8 X 8 example
.1.1.0.0.0.0.1.1
.1.1.0.0.0.0.1.1
.1.0.0.0.0.0.0.1
.0.1.1.0.0.1.1.0
.0.1.1.0.0.1.1.0
.0.0.1.0.0.1.0.0
.1.1.0.0.0.0.1.1
.1.1.1.0.0.1.1.1
CROSSREFS
Sequence in context: A166664 A147393 A088187 * A343034 A145944 A355964
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 26 2008
STATUS
approved