A166800 Number of nX2 1..7 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, 0, 2016, 23485, 139417, 583175, 1954287, 5607782, 14335282, 33495930, 72818046, 149173467, 290729595, 543013497

Offset

1,4

Links

Table of n, a(n) for n=1..15.

Formula

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

Empirical a(n) = (32/(12)!)*(n-1)*(n-2)*(n-3)*(-2494800 - 1797300*n - 108018018n^2 + 25097225*n^3 + 12368202*n^4 + 1514529*n^5 + 93498*n^6 + 3405*n^7 + 78*n^8 + n^9).

Empirical G.f.: x^4*(x^9 + 184*x^8 - 572*x^7 - 2132*x^6 + 13622*x^5 - 27732*x^4 + 26008*x^3 - 8640*x^2 - 2723*x + 2016)/(1-x)^13. (End)

Example

Some solutions for n=4
...1.7...1.7...1.4...1.4...1.5...1.6...1.2...1.3...1.5...2.2...1.7...2.3...1.7
...2.3...2.7...3.2...3.3...1.7...2.6...3.6...1.5...2.4...4.5...3.3...6.4...3.2
...4.5...3.4...5.5...5.2...3.2...5.3...4.6...2.7...2.6...6.3...4.5...7.1...4.4
...4.6...6.5...6.7...7.6...4.6...7.4...5.7...6.4...3.7...7.1...6.2...7.5...5.6
------
...1.3...2.3...1.4...1.4...2.2...1.2...2.5...1.5...1.1...1.2...1.6...2.3...1.2
...2.6...5.3...5.2...2.5...3.5...4.2...3.5...3.2...2.7...5.2...2.5...5.1...3.4
...5.4...6.4...5.3...7.3...4.6...5.6...4.1...7.4...3.5...6.3...4.4...7.4...5.7
...5.7...7.1...6.7...7.6...7.1...7.3...7.6...7.6...6.4...7.4...7.3...7.6...6.6

Crossrefs

Sequence in context: A343178 A125491 A166818 * A223216 A110851 A282331

Adjacent sequences: A166797 A166798 A166799 * A166801 A166802 A166803

Keyword

nonn,more

Author

R. H. Hardin, Oct 21 2009

Status

approved