A205979 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two clockwise edge increases.

81, 423, 2232, 11568, 60432, 315357, 1643538, 8574615, 44720319, 233223303, 1216434498, 6344254641, 33088388283, 172573776357, 900058321935, 4694264219421, 24482997863997, 127691295254772, 665975373377820

Offset

1,1

Comments

Column 1 of A205986.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 10*a(n-2) + 35*a(n-3) + a(n-4) + 3*a(n-5) + a(n-6) + 2*a(n-7).

Empirical g.f.: 3*x*(27 + 87*x + 192*x^2 + 13*x^3 + 30*x^4 + 9*x^5 + 14*x^6) / (1 - 2*x - 10*x^2 - 35*x^3 - x^4 - 3*x^5 - x^6 - 2*x^7). - Colin Barker, Jun 13 2018

Example

Some solutions for n=4:
..2..1....1..2....2..2....2..0....1..1....2..0....0..1....2..1....2..0....2..2
..2..1....2..2....2..0....1..0....1..1....1..2....2..2....2..0....2..2....0..2
..0..2....0..2....0..2....0..0....0..2....1..2....2..2....0..1....0..2....2..0
..1..1....1..0....1..2....1..1....1..2....2..0....1..0....0..0....2..0....2..0
..1..2....1..1....0..1....2..0....0..1....0..0....2..0....0..1....2..2....2..1

Crossrefs

Cf. A205986.

Sequence in context: A206668 A238180 A206414 * A206661 A238173 A206407

Adjacent sequences: A205976 A205977 A205978 * A205980 A205981 A205982

Keyword

nonn

Author

R. H. Hardin, Feb 02 2012

Status

approved