A206270 Number of (n+1) X 2 0..2 arrays with no 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward or upward neighbors.

81, 306, 1233, 4884, 19509, 77580, 309057, 1230480, 4900461, 19512618, 77701857, 309412494, 1232105853, 4906303206, 19537226541, 77798456808, 309798343185, 1233636035952, 4912416015885, 19561547012604, 77895299289393

Offset

1,1

Comments

Column 1 of A206277.

Links

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

Formula

Empirical: a(n) = 6*a(n-2) + 20*a(n-3) + 58*a(n-4) + 66*a(n-5) + 29*a(n-6) + 16*a(n-7).

Empirical g.f.: 3*x*(27 + 102*x + 249*x^2 + 476*x^3 + 431*x^4 + 174*x^5 + 88*x^6) / (1 - 6*x^2 - 20*x^3 - 58*x^4 - 66*x^5 - 29*x^6 - 16*x^7). - Colin Barker, Jun 15 2018

Example

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

Crossrefs

Cf. A206277.

Sequence in context: A206277 A236018 A206685 * A236011 A206678 A237463

Adjacent sequences: A206267 A206268 A206269 * A206271 A206272 A206273

Keyword

nonn

Author

R. H. Hardin, Feb 05 2012

Status

approved