A206088 Number of (n+1) X 3 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases.

270, 780, 2016, 5952, 17976, 54432, 165936, 504912, 1538496, 4687392, 14278656, 43507872, 132544416, 403832352, 1230343776, 3748436832, 11420384736, 34794057312, 106006675296, 322968189792, 983980623456, 2997875890272

Offset

1,1

Comments

Column 2 of A206094.

Links

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

Formula

Empirical: a(n) = a(n-1) + 6*a(n-2) + 4*a(n-3) - 10*a(n-4) for n>6.

Empirical g.f.: 6*x*(45 + 85*x - 64*x^2 - 304*x^3 - 82*x^4 + 80*x^5) / ((1 - x)*(1 - 6*x^2 - 10*x^3)). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206094.

Sequence in context: A292766 A180151 A278130 * A029770 A028529 A109025

Adjacent sequences: A206085 A206086 A206087 * A206089 A206090 A206091

Keyword

nonn

Author

R. H. Hardin, Feb 03 2012

Status

approved