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A146037 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 3X3 el 1,1 1,2 1,3 2,3 3,3 in any orientation. 0
1, 1, 1, 3, 7, 19, 89, 399, 1939, 11793, 102715, 985113, 13989079, 211198639, 4331591655, 98297746517, 2965968725989, 100683520176799 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..18.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.0.0.1.1.1

.1.1.1.0.0.0.0.1

.1.0.0.1.1.1.0.1

.1.0.1.0.0.1.0.0

.0.0.1.0.0.1.0.1

.1.0.1.1.1.0.0.1

.1.0.0.0.0.1.1.1

.1.1.1.0.0.0.0.0

CROSSREFS

Sequence in context: A322852 A243583 A215487 * A172514 A128024 A245723

Adjacent sequences:  A146034 A146035 A146036 * A146038 A146039 A146040

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified October 28 04:43 EDT 2021. Contains 348313 sequences. (Running on oeis4.)