A206047 Number of (n+1) X 2 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to one.

48, 255, 1338, 7041, 37020, 194691, 1023822, 5384085, 28313712, 148895799, 783011010, 4117687209, 21654034308, 113873925675, 598838568438, 3149163684861, 16560776867160, 87089576125791, 457985415203562

Offset

1,1

Comments

Column 1 of A206054.

Links

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

Formula

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

Empirical g.f.: 3*x*(16 + 21*x - 6*x^2) / (1 - 4*x - 7*x^2 + 2*x^3). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206054.

Sequence in context: A181773 A052683 A206054 * A223434 A235911 A235904

Adjacent sequences: A206044 A206045 A206046 * A206048 A206049 A206050

Keyword

nonn

Author

R. H. Hardin, Feb 03 2012

Status

approved