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A146052
Number of n X n binary arrays symmetric under 90 degree rotation 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, 1, 13, 33, 59, 183, 775, 3549, 21203, 124205, 885931, 6938155, 65072235, 697161911, 8870657391, 129325569203, 2224950934319, 42682217569275, 961782024725197, 24665663177266467
OFFSET
1,6
EXAMPLE
Maximal 8 X 8 example
.1.1.0.1.0.1.1.1
.1.1.0.1.1.0.1.1
.1.0.0.1.1.0.0.0
.0.1.1.0.0.1.1.1
.1.1.1.0.0.1.1.0
.0.0.0.1.1.0.0.1
.1.1.0.1.1.0.1.1
.1.1.1.0.1.0.1.1
CROSSREFS
Sequence in context: A213686 A050659 A123161 * A082109 A024839 A146177
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 26 2008
STATUS
approved