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A145955 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation. 0
1, 1, 1, 3, 9, 23, 125, 821, 6239, 71403, 1048093, 19913069, 517074745, 17642361171, 795865550951, 47901047706833, 3815017258032049, 403246928224172293, 56605968541991726917, 10536114891916229568297, 2602764408693859006627701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.0.0.0.1.0

.0.0.0.0.0.0.1.1

.0.0.0.1.1.0.0.1

.0.0.1.0.1.1.0.0

.0.0.1.1.0.0.1.0

.0.0.0.1.0.0.1.1

.1.1.0.0.1.1.0.1

.0.1.1.0.0.1.1.0

CROSSREFS

Sequence in context: A116659 A147508 A146472 * A129834 A029488 A198681

Adjacent sequences:  A145952 A145953 A145954 * A145956 A145957 A145958

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 2008

STATUS

approved

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Last modified January 26 02:39 EST 2022. Contains 350572 sequences. (Running on oeis4.)