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A166802
Number of nX3 1..4 arrays containing at least one of each value, all equal values connected, rows considered as a single number in nondecreasing order, and columns considered as a single number in nondecreasing order.
0
0, 67, 720, 3909, 15112, 47308, 127874, 309807, 689082, 1430425, 2804306, 5238541
OFFSET
1,2
FORMULA
From G. C. Greubel, May 27 2016: (Start)
Empirical a(n) = (1/181440)*(n-1)*(181440 - 405504*n + 100296*n^2 + 573392*n^3 + 307532*n^4 + 67775*n^5 + 9815*n^6 + 569*n^7 + 29*n^8).
Empirical G.f.: x^2*(x^8 - 6*x^7 + 7*x^6 + 70*x^5 - 237*x^4 + 382*x^3 - 276*x^2 + 50*x + 67)/(1-x)^10.
Empirical E.g.f.: (1/181440)*(-181440 + 181440*x + 5987520*x^2 + 15724800*x^3 + 10810800*x^4 + 3172176*x^5 + 472500*x^6 + 37764*x^7 + 1584*x^8 + 29*x^9)*exp(x) + 1. (End)
EXAMPLE
Some solutions for n=4
...1.1.4...1.3.4...1.1.1...1.1.2...1.1.3...1.2.2...1.1.2...1.2.2...1.2.3
...1.2.4...1.3.4...1.2.3...1.3.2...1.3.3...4.2.2...2.2.2...3.2.2...1.3.3
...1.4.4...1.4.4...3.3.3...1.3.3...2.4.3...4.2.3...2.3.2...3.4.4...1.3.3
...3.3.4...4.4.2...4.4.3...4.3.3...4.4.4...4.4.4...4.3.2...3.4.4...1.4.3
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...1.1.2...1.1.2...1.3.3...1.1.2...1.1.4...1.3.4...1.1.1...1.1.2...1.3.4
...1.3.2...1.3.2...2.3.4...1.4.3...2.2.2...1.3.4...1.1.3...1.2.2...1.4.4
...3.3.2...3.3.2...4.4.4...4.4.4...2.3.3...2.2.4...1.4.2...4.2.2...1.4.4
...4.4.4...3.4.4...4.4.4...4.4.4...3.3.3...4.4.4...4.4.4...4.4.3...2.2.4
CROSSREFS
Sequence in context: A178004 A106106 A093942 * A212557 A254640 A093267
KEYWORD
nonn,more
AUTHOR
R. H. Hardin, Oct 21 2009
STATUS
approved