A233726 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal.

40, 148, 556, 2104, 7976, 30260, 114820, 435720, 1653488, 6274804, 23812172, 90364680, 342924296, 1301361476, 4938528804, 18741194360, 71120848176, 269896091748, 1024227097996, 3886833426776, 14750121431720, 55975149559572

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 4*x*(10 + 7*x - 22*x^2 - 6*x^3) / (1 - 3*x - 5*x^2 + 7*x^3 + 2*x^4). - Colin Barker, Oct 11 2018

Example

Some solutions for n=5:
..0..2....3..1....3..2....0..2....2..3....0..1....0..1....1..3....0..2....3..0
..2..1....2..0....2..0....1..3....1..0....1..3....1..3....0..2....1..3....2..1
..0..2....1..2....0..1....0..1....0..2....2..1....0..1....2..1....3..2....3..0
..2..3....0..3....2..3....3..2....2..1....0..2....2..0....1..3....0..1....2..1
..1..0....1..2....3..1....0..1....0..2....2..1....0..1....0..2....2..0....0..2
..3..2....2..0....1..0....1..3....1..0....1..3....1..3....1..3....0..1....2..1

Crossrefs

Column 1 of A233733.

Sequence in context: A044753 A160148 A233733 * A100766 A189541 A201233

Adjacent sequences: A233723 A233724 A233725 * A233727 A233728 A233729

Keyword

nonn

Author

R. H. Hardin, Dec 15 2013

Status

approved