The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A166826 Number of n X 2 1..4 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. 1
 0, 4, 49, 219, 666, 1636, 3499, 6783, 12212, 20748, 33637, 52459, 79182, 116220, 166495, 233503, 321384, 434996, 579993, 762907, 991234, 1273524, 1619475, 2040031, 2547484, 3155580, 3879629, 4736619, 5745334, 6926476, 8302791, 9899199 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n=1..44 FORMULA Empirical: a(n) = (n^6 + 18*n^5 + 100*n^4 - 731*n^2 + 792*n - 180)/180. Conjectures from Colin Barker, Mar 26 2018: (Start) G.f.: x^2*(4 + 21*x - 40*x^2 + 22*x^3 - 2*x^4 - x^5) / (1 - x)^7. a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7. (End) EXAMPLE All solutions for n=3: ...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...1.1...2.1...2.1...2.1...2.1 ...2.1...2.1...2.2...3.1...3.2...3.2...3.2...3.3...4.2...2.1...2.1...2.2...2.2 ...3.4...4.3...4.3...4.2...3.4...4.2...4.4...4.2...4.3...3.4...4.3...3.4...4.3 ------ ...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1...2.1 ...2.3...2.3...2.3...2.4...2.4...3.1...3.1...3.1...3.3...3.3...3.3...3.4...3.4 ...2.4...4.3...4.4...3.3...3.4...3.4...4.1...4.4...3.4...4.3...4.4...3.4...4.4 ------ ...2.1...2.1...2.1...2.2...2.2...2.2...2.2...2.2...2.2...3.1...3.1...3.1...3.1 ...4.1...4.3...4.3...3.1...3.1...3.1...3.2...3.3...4.1...3.1...3.2...3.2...3.2 ...4.3...4.3...4.4...3.4...4.1...4.4...4.1...4.1...4.3...4.2...3.4...4.2...4.4 ------ ...3.1...3.1...3.1...3.1...3.2...3.2...3.2...3.2...3.3...4.1 ...3.3...4.1...4.2...4.2...3.2...3.3...4.1...4.1...4.1...4.2 ...4.2...4.2...4.2...4.4...4.1...4.1...4.1...4.4...4.2...4.3 CROSSREFS Sequence in context: A340662 A041065 A166838 * A295535 A078187 A100256 Adjacent sequences: A166823 A166824 A166825 * A166827 A166828 A166829 KEYWORD nonn AUTHOR R. H. Hardin, Oct 21 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 21 23:34 EDT 2024. Contains 373560 sequences. (Running on oeis4.)