A262414 Number of (n+1) X (2+1) 0..1 arrays with each row divisible by 3 and column not divisible by 3, read as a binary number with top and left being the most significant bits.

0, 4, 12, 48, 144, 468, 1404, 4320, 12960, 39204, 117612, 353808, 1061424, 3187188, 9561564, 28693440, 86080320, 258267204, 774801612, 2324483568, 6973450704, 20920588308, 62761764924, 188286003360, 564858010080, 1694576156004

Offset

1,2

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 3*a(n-2) - 9*a(n-3).

Empirical g.f.: 4*x^2 / ((1 - 3*x)*(1 - 3*x^2)). - Colin Barker, Dec 31 2018

Example

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

Crossrefs

Column 2 of A262420.

Sequence in context: A057346 A255230 A253087 * A081620 A282023 A149376

Adjacent sequences: A262411 A262412 A262413 * A262415 A262416 A262417

Keyword

nonn

Author

R. H. Hardin, Sep 22 2015

Status

approved