A147480 - OEIS

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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.

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