A206078 Number of (n+1) X 2 0..3 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to one.

124, 960, 7308, 55864, 426596, 3258496, 24887884, 190093096, 1451920276, 11089697360, 84702551132, 646953877560, 4941401481188, 37742178485600, 288272879761068, 2201813900709576, 16817344930171316, 128450043128179312

Offset

1,1

Comments

Column 1 of A206085.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) +13*a(n-2) -4*a(n-3) +2*a(n-4).

Empirical g.f.: 4*x*(31 + 54*x - 16*x^2 + 8*x^3) / (1 - 6*x - 13*x^2 + 4*x^3 - 2*x^4). - Colin Barker, Jun 13 2018

Example

Some solutions for n=4:
..1..1....2..3....1..2....3..3....2..3....0..0....3..3....0..2....1..0....1..1
..3..3....2..2....1..2....3..1....3..3....1..0....0..0....0..1....3..3....3..3
..3..0....0..1....1..1....3..1....1..2....2..3....2..2....0..0....2..2....1..1
..3..3....0..0....3..3....3..3....1..1....2..2....3..2....0..1....2..1....1..0
..2..2....0..3....2..2....3..1....1..2....1..1....0..1....0..0....1..1....3..3

Crossrefs

Cf. A206085.

Sequence in context: A038645 A038859 A206085 * A206197 A206190 A251381

Adjacent sequences: A206075 A206076 A206077 * A206079 A206080 A206081

Keyword

nonn

Author

R. H. Hardin, Feb 03 2012

Status

approved