A268419 Number of n X 1 0..3 arrays with every repeated value in every row unequal to the previous repeated value, and in every column equal to the previous repeated value, and new values introduced in row-major sequential order.

1, 2, 5, 14, 44, 147, 505, 1750, 6065, 20950, 72052, 246715, 841345, 2858714, 9682221, 32700942, 110173948, 370393059, 1242869721, 4163561358, 13927246329, 46526402422, 155249799428, 517505902283, 1723457914689, 5734951039346

Offset: 1

Author

R. H. Hardin, Feb 04 2016

Keywords

• nonn

Examples

			Some solutions for n=8:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..0....1....1....1....0....1....1....1....1....0....1....1....1....1....0....1
..0....2....1....2....0....0....1....2....0....1....0....2....0....2....0....0
..1....2....0....2....0....1....1....1....2....2....2....0....2....1....1....1
..2....3....2....1....0....2....0....2....3....0....1....0....0....3....0....1
..0....0....3....0....0....1....1....3....3....2....3....2....3....0....2....1
..3....2....0....3....0....0....2....3....3....0....1....0....2....2....1....2
..0....2....3....2....1....3....3....2....1....1....0....2....2....0....0....1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Column 1 of A268423.

Formula

Empirical: a(n) = 8*a(n-1) - 20*a(n-2) + 12*a(n-3) + 12*a(n-4) - 8*a(n-5) - 3*a(n-6).

Empirical g.f.: x*(1 - 6*x + 9*x^2 + 2*x^3 - 4*x^4 - x^5) / ((1 - x)*(1 - 3*x)*(1 - x - x^2)*(1 - 3*x - x^2)). - Colin Barker, Jan 13 2019