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A166761
Number of nX3 1..2 arrays containing at least one of each value, and all equal values connected.
1
4, 30, 106, 292, 712, 1618, 3518, 7432, 15404, 31526, 63986, 129164, 259824, 521498, 1045254, 2093232, 4189716, 8383278, 16771066, 33547380, 67100824, 134208610, 268425166, 536859352, 1073728892, 2147469238, 4294951298, 8589916892
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 14*a(n-2) + 16*a(n-3) -9*a(n-4) + 2*a(n-5).
From G. C. Greubel, May 26 2016: (Start)
Empirical a(n) = (3*2^(n + 5) - 2*n^3 - 9*n^2 - 73*n - 96)/3.
Empirical G.f.: (1/3)*( 96/(1 - 2*x) + 6*(-16 + 34*x - 25*x^2 + 5*x^3)/(1 - x)^4 ).
Empirical E.g.f.: (1/3)*(96*exp(x) - (96 + 84*x + 15*x^2 + 2*x^3 ) )*exp(x). (End)
EXAMPLE
Some solutions for n=4
...2.2.2...2.2.2...1.1.2...1.1.1...2.1.1...1.1.1...1.2.2...1.2.2...1.1.1
...2.1.1...1.2.2...1.2.2...2.2.1...2.2.2...2.1.1...1.2.2...1.2.2...1.2.1
...2.1.1...1.2.1...1.2.2...2.2.1...2.2.2...2.2.1...1.1.2...1.1.2...1.2.1
...2.2.1...1.1.1...1.1.2...2.2.1...2.2.2...2.2.2...2.2.2...1.1.1...1.1.1
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...1.2.2...2.2.2...1.1.2...1.1.1...1.1.1...1.1.2...1.2.2...1.2.2...1.1.1
...1.1.2...2.1.2...1.1.2...2.2.1...1.1.2...1.1.2...1.1.2...1.2.1...1.1.1
...1.1.2...1.1.1...1.2.2...2.2.1...1.1.2...1.1.2...1.1.2...1.1.1...2.2.1
...1.1.1...1.1.1...1.1.1...1.1.1...1.1.1...1.1.1...2.2.2...1.1.1...2.1.1
CROSSREFS
Sequence in context: A211624 A027297 A211628 * A213824 A333277 A027445
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 21 2009
STATUS
approved