A232370 Number of n X 2 0..3 arrays with every 0 next to a 1, every 1 next to a 2 and every 2 next to a 3 horizontally, diagonally or antidiagonally, and no adjacent values equal.

2, 14, 58, 230, 934, 3794, 15354, 62266, 252346, 1022806, 4145638, 16802922, 68105158, 276041834, 1118844570, 4534868126, 18380594246, 74499685134, 301959937342, 1223895154962, 4960655920226, 20106384977054, 81494609451994

Offset: 1

Author

R. H. Hardin, Nov 23 2013

Keywords

• nonn

Examples

			Some solutions for n=7:
..2..1....0..3....3..2....3..0....3..0....2..3....3..0....1..0....3..2....3..1
..0..3....2..1....1..2....1..2....1..0....0..1....1..0....1..2....1..0....2..1
..0..3....0..1....1..0....3..2....3..2....0..3....1..2....3..2....1..2....2..3
..2..1....2..1....3..0....1..2....1..2....2..3....3..0....3..2....3..2....2..3
..3..1....2..3....2..1....0..3....0..3....0..1....3..2....1..2....3..1....0..1
..0..2....2..1....2..3....0..1....2..1....3..2....1..0....3..0....2..1....0..1
..3..2....0..1....2..3....2..3....3..1....3..2....3..0....1..2....0..3....2..3
		

Links

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

Crossrefs

Column 2 of A232376.

Formula

Empirical: a(n) = 2*a(n-1) + 7*a(n-2) + 6*a(n-3) - 2*a(n-4) - 3*a(n-5) + 2*a(n-6) + a(n-7).

Empirical g.f.: 2*x*(1 + 5*x + 8*x^2 + 2*x^3 - 6*x^4 + x^5 + x^6) / ((1 + x)*(1 - 3*x - 4*x^2 - 2*x^3 + 4*x^4 - x^5 - x^6)). - Colin Barker, Oct 05 2018