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A144056 Number of n X n binary arrays, symmetric about both diagonal and antidiagonal, 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, 2, 3, 11, 31, 171, 719, 5907, 40576, 574191, 6118805, 134458817, 2328856652, 81657178991, 2239533631682, 126154274091928, 5530047112752039, 494646201440552586, 34629959352847199652, 4953721399562434015229 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..20.

CROSSREFS

Sequence in context: A080155 A235625 A032357 * A268687 A062630 A296005

Adjacent sequences:  A144053 A144054 A144055 * A144057 A144058 A144059

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 08 2008

STATUS

approved

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Last modified February 21 00:32 EST 2018. Contains 299388 sequences. (Running on oeis4.)