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A145760
Number of n X n binary arrays symmetric about main diagonal with all ones connected only either three adjacent vertically or three adjacent horizontally.
0
1, 1, 1, 3, 8, 27, 96, 569, 4093, 37611, 421080, 6366190, 123605120, 3088656877, 98116765714, 4039581343182, 214357411746908, 14651947137883915, 1285925403332066988, 145385760960996273023, 21168918836708595100735
OFFSET
1,4
CROSSREFS
Sequence in context: A340334 A319787 A148844 * A102318 A102206 A192856
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 17 2008
STATUS
approved