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A146131 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 3X2 zee 1,1 1,2 1,3 2,3 2,4 in any orientation. 0
1, 1, 1, 1, 1, 1, 5, 9, 21, 39, 159, 427, 2501, 9027, 58503, 271185, 2371669, 14600987, 167228191, 1344019107, 19775648697, 206847230557, 3987249030381, 54541478154327, 1370106516904685, 24431476697291095 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

Maximal 8 X 8 example

.0.0.1.1.1.0.0.0

.0.0.0.0.1.1.0.0

.1.0.0.0.0.0.1.0

.1.0.0.0.0.0.1.1

.1.1.0.0.0.0.0.1

.0.1.0.0.0.0.0.1

.0.0.1.1.0.0.0.0

.0.0.0.1.1.1.0.0

CROSSREFS

Sequence in context: A081883 A049744 A000323 * A083943 A097074 A050559

Adjacent sequences:  A146128 A146129 A146130 * A146132 A146133 A146134

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 27 2008

STATUS

approved

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Last modified December 2 17:48 EST 2021. Contains 349445 sequences. (Running on oeis4.)