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A146157 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only either as two by three or three by two blocks. 0
1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 6, 7, 16, 23, 50, 65, 176, 221, 727, 1056, 3742, 5997, 23258, 37914, 168488, 284282, 1460179, 2612520, 15176540, 28767703 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.1.1.0.0.0

.0.0.0.1.1.0.0.0

.0.0.0.1.1.0.0.0

.1.1.1.0.0.1.1.1

.1.1.1.0.0.1.1.1

.0.0.0.1.1.0.0.0

.0.0.0.1.1.0.0.0

.0.0.0.1.1.0.0.0

CROSSREFS

Sequence in context: A236971 A121211 A316585 * A238363 A255254 A048848

Adjacent sequences:  A146154 A146155 A146156 * A146158 A146159 A146160

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 27 2008

STATUS

approved

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Last modified February 23 18:13 EST 2019. Contains 320437 sequences. (Running on oeis4.)