A166781 Number of nX3 1..2 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.

4, 17, 44, 91, 164, 269, 412, 599, 836, 1129, 1484, 1907, 2404, 2981, 3644, 4399, 5252, 6209, 7276, 8459, 9764, 11197, 12764, 14471, 16324, 18329, 20492, 22819, 25316, 27989, 30844, 33887, 37124, 40561, 44204, 48059, 52132, 56429, 60956, 65719, 70724

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Formula

Empirical: a(n) = n^3 + n^2 + 3*n - 1.

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

Empirical G.f.: x*(x^3 + x + 4)/(1-x)^4.

Empirical E.g.f.: (-1 + 5*x + 4*x^2 + x^3)*exp(x) + 1. (End)

Example

Some solutions for n=4
...1.1.2...1.1.1...1.1.1...1.1.1...2.2.1...1.1.1...1.1.1...1.1.2...1.1.1
...1.1.2...2.1.2...1.1.2...1.1.1...2.2.1...1.1.1...1.2.1...2.1.2...2.2.1
...1.2.2...2.2.2...2.2.2...1.1.2...2.2.1...1.2.1...1.2.2...2.1.2...2.2.1
...2.2.2...2.2.2...2.2.2...1.1.2...2.2.2...1.2.1...2.2.2...2.2.2...2.2.2
------
...1.1.1...1.2.2...1.1.1...1.2.2...2.1.1...1.1.1...2.2.1...2.1.2...1.1.1
...1.1.1...2.2.2...1.1.2...1.2.2...2.2.1...1.1.1...2.2.1...2.1.2...1.1.1
...1.1.1...2.2.2...1.1.2...1.2.2...2.2.1...1.1.2...2.2.2...2.1.2...1.1.1
...2.2.1...2.2.2...2.2.2...1.2.2...2.2.2...1.2.2...2.2.2...2.2.2...2.1.1

Crossrefs

Sequence in context: A018973 A212575 A162148 * A376232 A147656 A095667

Adjacent sequences: A166778 A166779 A166780 * A166782 A166783 A166784

Keyword

nonn

Author

R. H. Hardin, Oct 21 2009

Status

approved