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A166760 Number of nX2 1..7 arrays containing at least one of each value, and all equal values connected. 0
0, 0, 0, 50400, 1380960, 16803360, 129764880, 740028240, 3386113920, 13088718720, 44246270880, 134067769920, 370807123680, 949269877920 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..14.

FORMULA

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

Empirical a(n) = (1/1485)*(n-1)*(n-2)*(n-3)*(64*n^9 - 768*n^8 + 9648*n^7 - 73200*n^6 + 407526*n^5 - 1667892*n^4 + 4855097*n^3 - 9499725*n^2 + 11240730*n - 6237000).

Empirical G.f.: 5040*x^4*(5*x^9 + 44*x^8 + 187*x^7 + 452*x^6 + 827*x^5 + 958*x^4 + 917*x^3 + 552*x^2 + 144*x + 10)/(1-x)^13.

Empirical E.g.f.: (1/1485)*(37422000 - 37422000*x + 18711000*x^2 - 6237000*x^3 + 4677750*x^4 + 13659030*x^5 + 19178775*x^6 + 11594880*x^7 + 3632310*x^8 + 628320*x^9 + 60720*x^10 + 3072*x^11 + 64*x^12)*exp(x) - 25200. (End)

EXAMPLE

Some solutions for n=4

...4.5...7.6...4.2...4.2...5.3...5.3...2.2...6.1...7.4...7.5...7.5...2.4...4.5

...3.6...1.1...1.6...1.3...2.4...4.1...5.4...7.1...3.2...4.1...4.2...2.7...4.7

...3.2...2.5...5.7...5.5...2.1...7.7...1.7...3.5...6.2...2.6...3.6...5.6...6.2

...7.1...3.4...5.3...7.6...6.7...2.6...3.6...4.2...5.1...2.3...1.6...3.1...3.1

------

...1.7...1.6...4.1...4.3...3.1...2.3...6.3...5.5...2.3...5.7...2.7...1.5...2.1

...3.2...2.2...3.2...5.1...7.2...5.5...7.1...7.1...1.7...3.4...2.4...2.6...4.4

...6.4...7.3...5.6...7.7...5.2...4.7...7.4...4.2...1.4...3.1...6.1...3.7...5.3

...6.5...5.4...7.6...2.6...4.6...6.1...2.5...3.6...5.6...2.6...3.5...3.4...6.7

CROSSREFS

Sequence in context: A237949 A251466 A267252 * A231918 A029823 A302902

Adjacent sequences:  A166757 A166758 A166759 * A166761 A166762 A166763

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 21 2009

STATUS

approved

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Last modified April 14 22:25 EDT 2021. Contains 342962 sequences. (Running on oeis4.)