A206678 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having an unequal number of clockwise and counterclockwise edge increases.

81, 306, 1404, 5352, 24336, 93696, 422016, 1639296, 7321728, 28666368, 127080960, 501063168, 2206534656, 8754665472, 38325454848, 152909291520, 665878216704, 2669887807488, 11572292272128, 46604992118784, 201163253317632

Offset

1,1

Comments

Column 1 of A206685.

Links

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

Formula

Empirical: a(n) = 16*a(n-2) + 4*a(n-3) + 8*a(n-4).

Empirical g.f.: 3*x*(27 + 102*x + 36*x^2 + 44*x^3) / (1 - 16*x^2 - 4*x^3 - 8*x^4). - Colin Barker, Jun 17 2018

Example

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

Crossrefs

Cf. A206685.

Sequence in context: A206685 A206270 A236011 * A237463 A237456 A183994

Adjacent sequences: A206675 A206676 A206677 * A206679 A206680 A206681

Keyword

nonn

Author

R. H. Hardin, Feb 11 2012

Status

approved