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A146022 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation. 0
1, 1, 1, 5, 21, 39, 231, 1367, 12771, 121235, 1706171, 26315137, 652740079, 17081149001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.1.1.1.1.0

.1.0.0.0.0.0.1.0

.1.1.1.1.0.0.0.1

.0.0.0.0.1.1.1.1

.1.1.1.1.0.0.0.0

.1.0.0.0.1.1.1.1

.0.1.0.0.0.0.0.1

.0.1.1.1.1.0.0.0

CROSSREFS

Sequence in context: A038844 A303521 A147345 * A054286 A031292 A147331

Adjacent sequences:  A146019 A146020 A146021 * A146023 A146024 A146025

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified December 9 06:07 EST 2021. Contains 349627 sequences. (Running on oeis4.)