A267975 Number of 1 X n 0..3 arrays with every repeated value in every row greater than or equal to, and in every column greater than, the previous repeated value.
4, 16, 64, 250, 964, 3674, 13868, 51917, 192980, 712868, 2618876, 9573915, 34845780, 126322410, 456285828, 1642687662, 5895922368, 21102304252, 75332038300, 268275675007, 953247943192, 3380004168904, 11961143709736, 42249741430325
Offset: 1
Keywords
Examples
Some solutions for n=8: ..0..0..3..1..1..2..2..1....3..2..0..1..3..2..1..1....2..1..2..2..0..1..2..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A267974.
Formula
Empirical: a(n) = 12*a(n-1) - 50*a(n-2) + 72*a(n-3) + 21*a(n-4) - 72*a(n-5) - 50*a(n-6) - 12*a(n-7) -a(n-8).
Empirical g.f.: x*(4 - 32*x + 72*x^2 - 6*x^3 - 72*x^4 - 50*x^5 - 12*x^6 - x^7) / (1 - 3*x - x^2)^4. - Colin Barker, Feb 26 2018
Comments