A166778 Number of nX2 1..5 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.

0, 0, 160, 1245, 5326, 16876, 44382, 102609, 215668, 421056, 774852, 1358269, 2285778, 3715036, 5858866, 8999553, 13505736, 19852192, 28642824, 40637181, 56780854, 78240108, 106441126, 143114257, 190343676, 250622880

Offset

1,3

Links

Table of n, a(n) for n=1..26.

Formula

Empirical: a(n) = (1/2520)*(n-1)*(n-2)*(n^6 + 35*n^5 + 551*n^4 + 4033*n^3 + 8106*n^2 -11790*n + 1260).

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

Empirical G.f.: x^3*(x^6 + 33*x^5 - 186*x^4 + 322*x^3 - 119*x^2 - 195*x + 160) ) /(1-x)^9.

Empirical E.g.f.: (1/2520)*(2520 - 2520*x + 1260*x^2 + 66780*x^3 + 63630*x^4 + 14700*x^5 + 1386*x^6 + 60*x^7 + x^8)*exp(x) - 1. (End)

Example

Some solutions for n=4
...1.3...1.3...3.2...1.1...2.1...2.1...2.1...1.3...2.2...1.3...3.1...4.2...1.3
...2.3...1.4...4.1...3.3...2.4...2.3...2.4...2.5...2.4...2.3...3.3...4.3...1.3
...2.3...2.5...4.4...4.4...5.3...3.3...3.3...4.5...3.1...5.4...4.3...5.1...2.5
...5.4...2.5...5.5...5.2...5.3...5.4...5.5...5.5...5.5...5.5...5.2...5.1...4.4
------
...2.2...1.1...1.1...2.2...1.1...1.1...1.1...1.3...1.1...2.1...2.3...1.3...1.1
...4.4...2.4...2.5...2.4...1.2...3.1...1.1...2.4...1.2...3.3...4.4...1.3...4.2
...5.1...3.4...3.3...3.4...4.4...3.5...2.5...4.4...1.4...3.4...5.1...2.4...5.3
...5.3...3.5...4.4...5.1...5.3...4.2...3.4...5.4...3.5...3.5...5.1...5.5...5.3

Crossrefs

Sequence in context: A305272 A234450 A234444 * A236518 A120103 A235655

Adjacent sequences: A166775 A166776 A166777 * A166779 A166780 A166781

Keyword

nonn

Author

R. H. Hardin, Oct 21 2009

Status

approved