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A163047
Number of nX3 binary arrays with all 1s connected, and all corners 1
1
1, 3, 12, 58, 293, 1481, 7484, 37832, 191285, 967235, 4890912, 24731434, 125057361, 632367297, 3197640264, 16169248032, 81761725337, 413437887795, 2090597850596, 10571356673930, 53455322317101, 270303194968521, 1366820253696484
OFFSET
1,2
LINKS
FORMULA
For n>6, a(n) = 7*a(n-1) - 11*a(n-2) + 6*a(n-3) + a(n-4) - 7*a(n-5) + a(n-6). [From Max Alekseyev, Aug 01 2009]
G.f.: -x*(x-1)*(x^2+3*x-1)/(-1+7*x-11*x^2+6*x^3+x^4-7*x^5+x^6). [From R. J. Mathar, Aug 11 2009]
CROSSREFS
Sequence in context: A079245 A122677 A038177 * A369616 A372378 A369594
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 20 2009
STATUS
approved