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A146057 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 2X3 U in any orientation. 0
1, 1, 1, 1, 5, 13, 31, 133, 759, 5033, 38887, 382421, 4832387, 75700651, 1478349269, 35999240895, 1090549247319, 41238833131575, 1952862897511921, 115606424326327149, 8526463138185345657, 783968967361577289677 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..22.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.1.1.0.0.0

.0.0.0.1.0.0.0.0

.0.0.0.1.1.0.0.0

.1.1.1.0.0.1.0.1

.1.0.1.0.0.1.1.1

.0.0.0.1.1.0.0.0

.0.0.0.0.1.0.0.0

.0.0.0.1.1.0.0.0

CROSSREFS

Sequence in context: A146376 A146368 A147424 * A062403 A066688 A046789

Adjacent sequences:  A146054 A146055 A146056 * A146058 A146059 A146060

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified October 16 21:10 EDT 2019. Contains 328103 sequences. (Running on oeis4.)