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A145864
Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in two by two blocks.
0
1, 2, 1, 4, 8, 25, 59, 294, 976, 6868, 36894, 351022, 2656603, 36966909, 391525649, 7896337875, 122564741600, 3503953133171, 77993874405982, 3210152559844391, 101979707965980254, 6040428902857902560, 276387013896712513044
OFFSET
1,2
EXAMPLE
Maximal 7 X 7 example
.1.1.0.1.1.0.0
.1.1.0.1.1.0.0
.0.0.0.0.0.1.1
.1.1.0.0.0.1.1
.1.1.0.0.0.0.0
.0.0.1.1.0.1.1
.0.0.1.1.0.1.1
CROSSREFS
Sequence in context: A319479 A303632 A133267 * A306392 A182739 A359132
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 22 2008
STATUS
approved