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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.
0
1, 2, 1, 5, 17, 65, 213, 1787, 9524, 116339, 1060737, 20603151, 287231280, 9041569891, 204033795980, 10154300111410, 365136416788873, 29097460058976118, 1667205355351243670
OFFSET
1,2
CROSSREFS
Sequence in context: A063635 A192264 A144054 * A013014 A012905 A254677
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 08 2008
STATUS
approved