A166779 Number of nX2 1..6 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.

0, 0, 120, 2280, 15266, 65553, 217460, 607565, 1499964, 3370950, 7034048, 13819102, 25822302, 46247695, 79864876, 133612235, 217380376, 345016156, 535594248, 815010244

Offset

1,3

Links

Table of n, a(n) for n=1..20.

Formula

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

Empirical a(n) = (1/226800)*(n-1)*(n-2)*(2*n^8 + 106*n^7 + 2819*n^6 + 41065*n^5 + 264893*n^4 + 73939*n^3 - 3091374*n^2 + 1937430*n - 113400).

Empirical G.f.: x^3*(x^8 + 121*x^7 - 664*x^6 + 1010*x^5 + 593*x^4 - 3227*x^3 + 3214*x^2 - 960*x - 120)/(x-1)^11.

Empirical E.g.f.: (1/226800)*(-226800 + 226800*x - 113400*x^2 + 4573800*x^3 + 17000550*x^4 + 9576630*x^5 + 1813140*x^6 + 160920*x^7 + 7605*x^8 + 190*x^9 + 2*x^10)*exp(x) + 1. (End)

Example

Some solutions for n=4
...3.2...4.1...2.4...3.5...2.1...2.2...1.5...1.4...1.1...1.4...4.1...2.2...4.4
...3.6...4.2...2.4...4.4...2.4...3.6...2.6...2.5...1.4...2.4...4.3...3.3...5.3
...4.1...4.3...5.1...6.1...3.5...4.1...3.3...3.3...3.6...3.5...5.2...5.1...6.1
...5.5...6.5...6.3...6.2...3.6...5.1...4.4...3.6...5.2...6.6...5.6...6.4...6.2
------
...1.5...2.6...1.3...1.2...2.3...1.3...2.6...1.5...2.5...1.2...3.1...5.1...2.1
...2.4...3.3...1.6...3.3...5.1...5.5...3.1...6.2...4.3...3.5...4.2...5.3...2.1
...4.4...3.4...2.2...4.5...5.5...6.2...4.5...6.3...4.4...3.6...5.2...5.4...4.5
...6.3...5.1...5.4...6.5...6.4...6.4...5.5...6.4...6.1...4.6...6.2...6.2...6.3

Crossrefs

Sequence in context: A084030 A056291 A056286 * A038745 A267839 A220050

Adjacent sequences: A166776 A166777 A166778 * A166780 A166781 A166782

Keyword

nonn

Author

R. H. Hardin, Oct 21 2009

Status

approved