A232922 Number of 3 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally.

27, 54, 246, 912, 3612, 13992, 54600, 212544, 828048, 3225120, 12562464, 48931776, 190594944, 742387008, 2891677248, 11263389888, 43872104640, 170886518976, 665621195712, 2592665453760, 10098708106176, 39335543742144

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 4*a(n-2) - 2*a(n-3) for n>4.

Empirical g.f.: 3*x*(9 - 9*x - 8*x^2 + 4*x^3) / (1 - 3*x - 4*x^2 + 2*x^3). - Colin Barker, Oct 06 2018

Example

Some solutions for n=5:
..2..2..2..1..2....0..1..0..0..0....1..2..2..2..1....2..1..2..1..2
..2..2..2..2..2....0..1..0..0..0....1..2..1..2..2....2..1..2..1..0
..2..2..1..2..2....2..1..0..1..0....1..0..1..2..2....2..1..2..1..2

Crossrefs

Row 3 of A232920.

Sequence in context: A043323 A033903 A175806 * A306761 A181874 A042444

Adjacent sequences: A232919 A232920 A232921 * A232923 A232924 A232925

Keyword

nonn

Author

R. H. Hardin, Dec 02 2013

Status

approved