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A146151 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation. 0
1, 1, 1, 3, 9, 27, 119, 633, 3943, 30791, 332473, 4676705, 79725173, 1817184081, 50545874411, 1811092006865 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..16.

EXAMPLE

Maximal 8 X 8 example

.0.1.1.0.0.1.1.0

.1.1.0.0.0.0.1.1

.1.0.0.1.0.0.0.1

.0.0.1.1.0.1.1.0

.0.1.1.0.1.1.0.0

.1.0.0.0.1.0.0.1

.1.1.0.0.0.0.1.1

.0.1.1.0.0.1.1.0

CROSSREFS

Sequence in context: A148930 A230951 A121746 * A254334 A028855 A143014

Adjacent sequences:  A146148 A146149 A146150 * A146152 A146153 A146154

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 27 2008

STATUS

approved

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Last modified December 6 00:38 EST 2016. Contains 278771 sequences.