A233675 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the sum of the squares of the edge differences equal to 6.

48, 184, 648, 2440, 8712, 32456, 116872, 432456, 1565704, 5768392, 20957064, 76995656, 280355592, 1028180936, 3749152392, 13733970760, 50125386248, 183485530824, 670067844488, 2451649137224, 8956514967816, 32760264743368

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 12*a(n-2) - 4*a(n-3) - 16*a(n-4).

Empirical g.f.: 8*x*(6 + 17*x - 14*x^2 - 28*x^3) / (1 - x - 12*x^2 + 4*x^3 + 16*x^4). - Colin Barker, Oct 11 2018

Example

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

Crossrefs

Column 1 of A233682.

Sequence in context: A131683 A066134 A233682 * A005911 A130566 A233792

Adjacent sequences: A233672 A233673 A233674 * A233676 A233677 A233678

Keyword

nonn

Author

R. H. Hardin, Dec 14 2013

Status

approved