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A146031 Number of n X n binary arrays symmetric under horizontal reflection 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, 1, 1, 1, 47, 87, 827, 1813, 23847, 61833, 1905275, 6035973, 614447855, 2474833329, 318082536355, 1576923345267, 332168016129555, 2011400450726835, 916006897110162895, 6848186045213206995, 6424521065702879448173 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

Maximal 8 X 8 example

.1.1.1.0.0.1.1.1

.1.0.0.0.0.0.0.1

.1.0.0.0.0.0.0.1

.0.0.0.0.0.0.0.0

.0.0.0.0.0.0.0.0

.1.0.0.0.0.0.0.1

.1.0.0.0.0.0.0.1

.1.1.1.0.0.1.1.1

CROSSREFS

Sequence in context: A190799 A246873 A033232 * A272879 A139968 A132451

Adjacent sequences:  A146028 A146029 A146030 * A146032 A146033 A146034

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified October 26 18:30 EDT 2021. Contains 348268 sequences. (Running on oeis4.)