A166828 - OEIS

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A166828

Number of n X 2 1..6 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 nonincreasing order.

0, 0, 30, 728, 5364, 24402, 84285, 242793, 614140, 1407960, 2987500, 5953706, 11263472, 20392138, 35552387, 59984019, 98331688, 157130592, 245423322

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..19.

FORMULA

From G. C. Greubel, May 25 2016: (Start)

Empirical: a(n) = (16/(10)!)*(n-1)*(n-2)*(n^8 + 53*n^7 + 1342*n^6 + 17630*n^5 + 91114*n^4 - 102013*n^3 - 1246977*n^2 + 1575810*n - 113400).

Empirical G.f.: (1 - 11*x + 55*x^2 - 195*x^3 - 68*x^4 + 532*x^5 - 26*x^6 - 993*x^7 + 1077*x^8 - 461*x^9 + 73*x^10)/(x -1)^11 + 1.

Empirical E.g.f.: (16/(10)!)*(-226800 + 226800*x - 113400*x^2 + 1171800*x^3 + 5736150*x^4 + 3827250*x^5 + 799155*x^6 + 75870*x^7 + 3735*x^8 + 95*x^9 + x^10)*exp(x) + 1. (End)

EXAMPLE

All solutions for n=3

...4.3...4.3...3.1...3.1...3.1...3.1...3.2...3.2...3.2...3.2...3.1...3.1...3.2

...5.1...5.2...4.2...4.2...4.5...4.6...4.1...4.1...4.5...4.6...5.4...5.2...5.4

...6.2...6.1...5.6...6.5...6.2...5.2...5.6...6.5...6.1...5.1...6.2...6.4...6.1

------

...3.2...4.1...4.1...4.2...4.2...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1

...5.1...5.3...5.2...5.3...5.1...3.4...3.4...3.5...3.5...3.6...3.6...4.3...4.3

...6.4...6.2...6.3...6.1...6.3...5.6...6.5...6.4...4.6...5.4...4.5...5.6...6.5

------

...2.1...2.1...2.1...2.1

...4.5...4.6...5.3...5.4

...6.3...5.3...6.4...6.3

CROSSREFS

Sequence in context: A035520 A122186 A166840 * A053509 A273435 A259345

Adjacent sequences: A166825 A166826 A166827 * A166829 A166830 A166831

KEYWORD

nonn,more

AUTHOR

R. H. Hardin, Oct 21 2009

STATUS

approved