A166818 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 increasing order.

0, 0, 0, 2016, 23485, 139417, 583174, 1954280, 5607754, 14335198, 33495720, 72817584, 149172543, 290727879, 543010494

Offset

1,4

Links

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

Formula

Empirical: a(n) = ((2^5*4!)/(12)!)*binomial(n,4)*(n^8 + 78*n^7 + 3405*n^6 + 93498*n^5 + 1514529*n^4 + 12368202*n^3 + 25076435*n^2 - 107706168*n - 3335760). - G. C. Greubel, May 25 2016

Example

Some solutions for n=4
...1.2...1.1...1.2...3.7...2.3...2.5...1.5...1.2...1.4...1.2...2.3...2.7...1.2
...3.6...2.4...6.4...4.2...5.1...3.6...4.2...1.5...2.6...1.4...4.1...3.5...3.7
...3.7...3.7...6.5...5.2...6.4...4.1...4.3...6.4...5.3...5.6...6.5...3.6...5.7
...4.5...6.5...7.3...6.1...7.4...4.7...7.6...7.3...5.7...7.3...7.7...4.1...6.4
------
...1.4...1.6...1.7...3.4...2.5...1.4...1.5...1.1...1.6...1.5...2.3...3.4...1.4
...2.6...4.7...2.5...6.2...4.4...5.7...2.5...3.4...2.3...2.3...4.6...5.2...2.5
...3.7...5.2...3.6...6.5...6.3...6.2...3.7...6.2...2.7...6.3...5.1...7.1...3.6
...5.7...5.3...4.4...7.1...7.1...6.3...4.6...7.5...4.5...7.4...5.7...7.6...7.7

Crossrefs

Sequence in context: A323469 A343178 A125491 * A166800 A223216 A110851

Adjacent sequences: A166815 A166816 A166817 * A166819 A166820 A166821

Keyword

nonn,more

Author

R. H. Hardin, Oct 21 2009

Status

approved