A166817 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 increasing order.

0, 0, 90, 1552, 9902, 41151, 133175, 364772, 885824, 1962990, 4046548, 7865396, 14558830, 25855557, 44312489, 73628216, 119048688, 187885564, 290170926

Offset

1,3

Links

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

Formula

Empirical: a(n) = (16/10!)*n*(n-1)*(n-2)*(361620 - 1844397*n + 175952*n^2 + 173779*n^3 + 23435*n^4 + 1477*n^5 + 53*n^6 + n^7). - G. C. Greubel, May 25 2016

Empirical g.f.: x^3*(90+562*x-2220*x^2+2739*x^3-1256*x^4-98*x^5+258*x^6-59*x^7) / (1-x)^11. - Colin Barker, May 25 2016

Example

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

Crossrefs

Sequence in context: A279438 A250869 A234983 * A166799 A001561 A296998

Adjacent sequences: A166814 A166815 A166816 * A166818 A166819 A166820

Keyword

nonn

Author

R. H. Hardin, Oct 21 2009

Status

approved