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A166776 Number of nX2 1..3 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order. 1
0, 12, 51, 135, 286, 530, 897, 1421, 2140, 3096, 4335, 5907, 7866, 10270, 13181, 16665, 20792, 25636, 31275, 37791, 45270, 53802, 63481, 74405, 86676, 100400, 115687, 132651, 151410, 172086, 194805, 219697, 246896, 276540, 308771, 343735, 381582 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n=1..83

FORMULA

Empirical: a(n) = (n^4 + 8*n^3 + 8*n^2 - 23*n + 6)/6.

From G. C. Greubel, May 26 2016: (Start)

Empirical G.f.: x^2*(x^3 - 9*x + 12)/(1-x)^5.

Empirical E.g.f.: (1/6)*(6 - 6*x + 39*x^2 + 14*x^3 + x^4)*exp(x) - 1. (End)

EXAMPLE

All solutions for n=3

...2.2...2.2...2.2...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1

...2.2...3.1...3.1...2.2...2.2...2.2...2.1...2.1...2.1...2.3...2.3...3.1...3.1

...3.1...3.1...3.3...2.3...3.2...3.3...2.3...3.1...3.3...2.3...3.3...3.1...3.3

------

...2.1...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.2...1.1

...3.3...2.2...2.2...2.2...1.2...1.2...1.2...1.3...1.3...3.2...3.2...3.3...2.2

...3.3...2.3...3.2...3.3...1.3...3.2...3.3...1.3...3.3...3.2...3.3...3.3...2.3

------

...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1

...2.2...2.2...2.1...2.1...2.1...2.3...2.3...1.2...1.2...1.2...1.1...1.1...1.3

...3.2...3.3...2.3...3.1...3.3...2.3...3.3...1.3...3.2...3.3...2.3...3.2...2.2

------

...1.1...1.1...1.1...1.1...1.3...1.3...1.3...1.3...1.3...3.1...3.1...3.1

...1.3...3.2...3.2...3.1...2.2...2.3...2.3...1.3...1.3...3.2...3.2...3.1

...2.3...3.2...3.3...3.2...2.2...2.3...3.3...2.2...2.3...3.2...3.3...3.2

CROSSREFS

Sequence in context: A051797 A145886 A268351 * A200887 A236770 A115680

Adjacent sequences:  A166773 A166774 A166775 * A166777 A166778 A166779

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 21 2009

STATUS

approved

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Last modified February 22 06:17 EST 2018. Contains 299430 sequences. (Running on oeis4.)