A144058 Number of n X n binary arrays, symmetric under 90-degree rotation, with every 1 adjacent to at least one other 1, but at most one 1 adjacent horizontally and at most one 1 adjacent vertically.

1, 2, 1, 5, 17, 65, 213, 1787, 9524, 116339, 1060737, 20603151, 287231280, 9041569891, 204033795980, 10154300111410, 365136416788873, 29097460058976118, 1667205355351243670

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Crossrefs

Sequence in context: A063635 A192264 A144054 * A013014 A012905 A254677

Adjacent sequences: A144055 A144056 A144057 * A144059 A144060 A144061

Keyword

nonn

Author

R. H. Hardin, Sep 08 2008

Status

approved