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A145936 Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 elbow 1,1 1,2 2,1 in any orientation. 0
1, 1, 1, 1, 37, 75, 977, 2665, 132837, 502325, 101974497, 552478421, 221452649907, 1674265239081, 2145488824056353, 22931334677663557, 82765846278441676383, 1247574812306982208727, 12188412484958400688433357 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..19.

EXAMPLE

Maximal 8 X 8 example

.1.1.0.0.0.0.1.1

.1.0.0.0.0.0.0.1

.0.0.0.0.0.0.0.0

.1.1.0.0.0.0.1.1

.1.0.0.0.0.0.0.1

.0.1.1.0.0.1.1.0

.1.0.1.0.0.1.0.1

.1.1.0.0.0.0.1.1

CROSSREFS

Sequence in context: A087531 A283718 A085959 * A071884 A216287 A216329

Adjacent sequences:  A145933 A145934 A145935 * A145937 A145938 A145939

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 2008

STATUS

approved

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Last modified July 25 09:49 EDT 2021. Contains 346289 sequences. (Running on oeis4.)