A205980 Number of (n+1) X 3 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two clockwise edge increases.

423, 1980, 8004, 33504, 140802, 591336, 2482596, 10425528, 43778766, 183827574, 771932004, 3241441338, 13611219624, 57155642244, 240004267116, 1007811633786, 4231945805718, 17770531374384, 74620975427586, 313344031580448

Offset

1,1

Comments

Column 2 of A205986.

Links

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

Formula

Empirical: a(n) = a(n-1) + 7*a(n-2) + 26*a(n-3) + 5*a(n-4) - 12*a(n-6) - 4*a(n-7) for n>9.

Empirical g.f.: 3*x*(141 + 519*x + 1021*x^2 + 214*x^3 - 775*x^4 - 666*x^5 - 134*x^6 + 220*x^7 + 96*x^8) / (1 - x - 7*x^2 - 26*x^3 - 5*x^4 + 12*x^6 + 4*x^7). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A205986.

Sequence in context: A365865 A348099 A096024 * A206662 A205831 A206408

Adjacent sequences: A205977 A205978 A205979 * A205981 A205982 A205983

Keyword

nonn

Author

R. H. Hardin, Feb 02 2012

Status

approved