A166777 Number of nX2 1..4 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.

0, 12, 116, 487, 1438, 3472, 7342, 14119, 25268, 42732, 69024, 107327, 161602, 236704, 338506, 474031, 651592, 880940, 1173420, 1542135, 2002118, 2570512, 3266758, 4112791, 5133244, 6355660, 7810712, 9532431, 11558442, 13930208

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..45

Formula

Empirical: a(n) = (2*n^6 + 36*n^5 + 215*n^4 + 60*n^3 - 1297*n^2 + 1164*n - 180)/180.

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

Empirical G.f.: -x^2*(x-2)*(x^4 + 9*x^3 - 27*x^2 + 19*x + 6)/(1-x)^7.

Empirical E.g.f.: (1/180)*(-180 + 180*x + 990*x^2 + 2430*x^3 + 705*x^4 + 66*x^5 + 2*x^6)*exp(x) + 1. (End)

Example

Some solutions for n=4
...1.1...1.3...1.1...2.1...3.2...2.1...1.2...3.1...1.2...1.1...1.1...1.1...2.1
...2.2...1.4...1.2...3.4...3.2...2.4...1.2...3.2...1.3...1.2...2.1...3.2...3.1
...3.3...2.4...3.3...3.4...3.3...3.3...1.3...3.2...4.4...3.4...3.3...3.2...4.4
...4.4...4.4...4.3...3.4...4.1...3.3...1.4...3.4...4.4...4.4...4.4...4.4...4.4
------
...1.1...2.3...1.2...2.2...3.1...1.1...1.1...1.1...2.1...1.1...2.2...1.2...2.1
...2.1...2.3...2.2...2.2...3.2...1.1...4.2...3.3...2.1...2.1...3.2...3.2...3.1
...2.1...4.1...3.3...3.1...4.2...3.2...4.2...3.3...3.3...4.1...3.3...3.4...3.3
...4.3...4.4...3.4...4.4...4.2...4.2...4.3...4.2...3.4...4.3...4.1...4.4...3.4

Crossrefs

Sequence in context: A154247 A016204 A238929 * A027285 A238930 A304827

Adjacent sequences: A166774 A166775 A166776 * A166778 A166779 A166780

Keyword

nonn

Author

R. H. Hardin, Oct 21 2009

Status

approved