A210269 Half the number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having two or three distinct clockwise edge differences.

35, 273, 2130, 16620, 129684, 1011912, 7895856, 61610640, 480742176, 3751187136, 29270169408, 228392449152, 1782125347584, 13905760747776, 108505376592384, 846657508568064, 6606390939571200, 51549062997460992, 402232613876871168

Offset

1,1

Comments

Column 1 of A210276.

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 12*a(n-3).

Empirical g.f.: x*(35 - 7*x - 54*x^2) / (1 - 8*x + 12*x^3). - Colin Barker, Jul 15 2018

Example

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

Crossrefs

Cf. A210276.

Sequence in context: A251931 A267627 A210276 * A219575 A219711 A055658

Adjacent sequences: A210266 A210267 A210268 * A210270 A210271 A210272

Keyword

nonn

Author

R. H. Hardin, Mar 19 2012

Status

approved