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A147480 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 1100-1111-1100 pattern in any orientation. 0
1, 1, 1, 1, 1, 9, 21, 73, 310, 1107, 5232, 33319, 240772, 2106289, 21011261, 262231181, 3633528079, 62517538899 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

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

EXAMPLE

Maximal 8 X 8 example

.0.0.1.1.0.0.0.0

.1.1.1.1.0.0.0.0

.0.0.1.1.0.0.1.1

.1.1.0.0.1.1.1.1

.1.1.1.1.0.0.1.1

.1.1.0.0.1.1.0.0

.0.0.0.0.1.1.1.1

.0.0.0.0.1.1.0.0

CROSSREFS

Sequence in context: A173084 A137340 A075640 * A146396 A146681 A269633

Adjacent sequences:  A147477 A147478 A147479 * A147481 A147482 A147483

KEYWORD

nonn

AUTHOR

R. H. Hardin

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)