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A146033 Number of n X n binary arrays symmetric about main diagonal 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, 3, 7, 15, 39, 189, 995, 5569, 37913, 366061, 4244909, 58320195, 974389263, 20855855835, 546928072163, 17575257415665, 693118931384501, 34026835620030291, 2054942936198627105, 152983262052724174217 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

Maximal 8 X 8 example

.1.1.1.0.0.1.1.1

.1.0.0.0.0.0.0.1

.1.0.1.1.1.0.0.1

.0.0.1.0.0.0.0.0

.0.0.1.0.1.1.1.0

.1.0.0.0.1.0.0.1

.1.0.0.0.1.0.0.1

.1.1.1.0.0.1.1.1

CROSSREFS

Sequence in context: A078161 A216616 A230958 * A147188 A050565 A097111

Adjacent sequences:  A146030 A146031 A146032 * A146034 A146035 A146036

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified November 30 02:18 EST 2021. Contains 349416 sequences. (Running on oeis4.)