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Search: id:A146051
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A146051 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation. +0
1
1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 13, 13, 35, 35, 181, 181, 1303, 1303, 13131, 13131, 161693, 161693, 2592581, 2592581, 57377381, 57377381, 1720164275, 1720164275 (list; graph; listen)
OFFSET

1,9

EXAMPLE

Maximal 9 X 9 example

.0.0.1.1.0.1.1.0.0

.0.0.1.1.0.1.1.0.0

.1.1.0.1.0.1.0.1.1

.1.1.1.0.0.0.1.1.1

.0.0.0.0.0.0.0.0.0

.1.1.1.0.0.0.1.1.1

.1.1.0.1.0.1.0.1.1

.0.0.1.1.0.1.1.0.0

.0.0.1.1.0.1.1.0.0

CROSSREFS

Sequence in context: A146193 A146727 A146426 this_sequence A146229 A146020 A145948

Adjacent sequences: A146048 A146049 A146050 this_sequence A146052 A146053 A146054

KEYWORD

nonn

AUTHOR

Ron Hardin (rhhardin(AT)att.net), Oct 26 2008

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Last modified December 7 08:40 EST 2009. Contains 170430 sequences.


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