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A145763
Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only either three adjacent vertically or three adjacent horizontally.
0
1, 1, 1, 1, 4, 7, 16, 35, 133, 363, 1590, 5600, 33892, 154647, 1163836, 6812622, 66760064, 504710757, 6331779830, 61565739001, 996948455181, 12487323542741, 259917683188595, 4189678086571772, 112326942697897637
OFFSET
1,5
CROSSREFS
Sequence in context: A108122 A192800 A027609 * A144916 A217289 A050357
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 17 2008
STATUS
approved