A166786 Number of nX4 1..2 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.

6, 31, 112, 317, 750, 1559, 2944, 5165, 8550, 13503, 20512, 30157, 43118, 60183, 82256

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Formula

Empirical: a(n) = (2*n^5 + 15*n^4 + 60*n^3 - 75*n^2 + 268*n - 90)/30.

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

Empirical G.f.: x*(3*x^5 - 2*x^4 - 10*x^3 + 16*x^2 - 5*x + 6)/(1-x)^6.

Empirical E.g.f.: (1/30)*(-90 + 270*x + 240*x^2 + 200*x^3 + 35*x^4 + 2*x^5)*exp(x) + 3. (End)

Example

Some solutions for n=4
...1.1.1.1...1.1.1.1...1.1.2.2...1.1.2.2...1.1.1.1...1.1.1.1...1.1.1.1
...2.1.1.1...2.2.2.2...2.1.1.2...1.1.2.2...2.1.1.2...1.1.2.1...2.1.1.1
...2.2.1.1...2.2.2.2...2.2.1.2...1.1.2.2...2.1.1.2...1.1.2.2...2.1.1.1
...2.2.2.2...2.2.2.2...2.2.2.2...2.2.2.2...2.2.2.2...1.2.2.2...2.2.1.1
------
...1.1.1.1...1.1.1.1...1.1.1.2...1.1.1.1...2.1.1.1...1.1.1.1...1.1.1.2
...1.1.1.2...1.2.1.1...1.1.1.2...1.1.1.1...2.1.1.1...2.1.2.1...1.2.1.2
...1.2.2.2...1.2.1.1...2.2.2.2...1.2.2.2...2.2.1.1...2.1.2.2...1.2.1.2
...2.2.2.2...2.2.2.1...2.2.2.2...1.2.2.2...2.2.2.1...2.2.2.2...1.2.2.2

Crossrefs

Sequence in context: A356608 A365301 A337574 * A003728 A216370 A225425

Adjacent sequences: A166783 A166784 A166785 * A166787 A166788 A166789

Keyword

nonn,more

Author

R. H. Hardin, Oct 21 2009

Status

approved