A251344 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock summing to 3 4 or 5.

51, 309, 1899, 11709, 72243, 445797, 2751003, 16976493, 104762403, 646491861, 3989520459, 24619449501, 151927356051, 937548239301, 5785638109947, 35703345104973, 220326406088067, 1359640814523957, 8390383964148267

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) + 3*a(n-2) - 12*a(n-3).

Empirical g.f.: 3*x*(17 + x - 36*x^2) / (1 - 6*x - 3*x^2 + 12*x^3). - Colin Barker, Nov 29 2018

Example

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

Crossrefs

Column 1 of A251351.

Sequence in context: A204956 A243462 A251351 * A245362 A219145 A155464

Adjacent sequences: A251341 A251342 A251343 * A251345 A251346 A251347

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved