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A144055 Number of n X n binary arrays, symmetric about main diagonal, with every 1 adjacent to at least one other 1, but at most one 1 adjacent horizontally and at most one 1 adjacent vertically. 0
1, 4, 13, 75, 765, 12167, 294579, 11514473, 740527130, 74320148705, 11850151989347, 3053892893918393, 1251352342040855094, 814829245618611538573, 849714505582240228227866 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

CROSSREFS

Sequence in context: A304598 A171756 A235385 * A012150 A012261 A012075

Adjacent sequences:  A144052 A144053 A144054 * A144056 A144057 A144058

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 08 2008

STATUS

approved

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Last modified May 27 13:00 EDT 2020. Contains 334657 sequences. (Running on oeis4.)