A209780 Half the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having exactly one duplicate clockwise edge difference.

64, 576, 5074, 44948, 397734, 3520628, 31161462, 275819644, 2441352670, 21609092620, 191268034094, 1692966274828, 14984912401894, 132635602320228, 1173994381706142, 10391348815984084, 91976700981777710, 814111206705377460

Offset

1,1

Comments

Column 1 of A209787.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) + 22*a(n-2) - 39*a(n-3) - 95*a(n-4) + 30*a(n-6).

Empirical g.f.: 2*x*(32 + 64*x - 183*x^2 - 373*x^3 + 7*x^4 + 120*x^5) / (1 - 7*x - 22*x^2 + 39*x^3 + 95*x^4 - 30*x^6). - Colin Barker, Jul 12 2018

Example

Some solutions for n=4:
..0..2....2..0....3..3....1..2....1..1....1..1....1..2....3..1....1..0....0..0
..0..1....2..2....0..3....0..2....3..2....2..1....0..2....3..3....0..0....1..0
..0..0....1..1....0..0....2..2....1..1....2..3....0..0....1..1....0..3....2..0
..2..2....0..1....3..3....0..0....1..0....1..3....0..1....3..1....2..1....2..1
..1..2....1..1....3..1....2..2....0..0....1..1....0..1....1..1....0..1....1..1

Crossrefs

Cf. A209787.

Sequence in context: A265636 A209787 A247841 * A330831 A177757 A301796

Adjacent sequences: A209777 A209778 A209779 * A209781 A209782 A209783

Keyword

nonn

Author

R. H. Hardin, Mar 13 2012

Status

approved