A183784 Half the number of (n+1) X 2 0..2 arrays with no 2 X 2 subblock having sum 4.

31, 216, 1500, 10428, 72468, 503676, 3500532, 24329052, 169088148, 1175174460, 8167536180, 56764911132, 394519788756, 2741938101756, 19056647102580, 132444930680028, 920500836944148, 6397540377615036, 44463319555825332

Offset

1,1

Comments

Column 1 of A183792.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 3*a(n-1) + 24*a(n-2) + 24*a(n-3).

Empirical g.f.: x*(31 + 123*x + 108*x^2) / (1 - 3*x - 24*x^2 - 24*x^3). - Colin Barker, Apr 04 2018

Example

Some solutions for 3 X 2:
..1..0....0..1....2..1....0..0....1..0....1..2....1..2....1..2....2..1....0..1
..1..1....0..2....2..2....2..1....2..2....0..2....2..0....2..2....0..2....2..0
..0..1....2..1....1..1....1..2....2..2....0..0....2..2....1..2....1..2....0..1

Crossrefs

Cf. A183792.

Sequence in context: A284899 A062393 A183792 * A042874 A221448 A001136

Adjacent sequences: A183781 A183782 A183783 * A183785 A183786 A183787

Keyword

nonn

Author

R. H. Hardin, Jan 07 2011

Status

approved