A232936 Number of n X 3 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, vertically or antidiagonally.

12, 26, 84, 252, 774, 2360, 7212, 22024, 67272, 205466, 627562, 1916768, 5854418, 17881234, 54614930, 166811210, 509494028, 1556155380, 4752989126, 14517127208, 44339883148, 135427981664, 413639750856, 1263386202642, 3858779756370

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 5*a(n-2) + 4*a(n-3) - a(n-5) for n>6.

Empirical g.f.: 2*x*(6 + 7*x - x^2 - 5*x^3 - x^4 + x^5) / ((1 + x)*(1 - 2*x - 3*x^2 - x^3 + x^4)). - Colin Barker, Oct 06 2018

Example

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

Crossrefs

Column 3 of A232941.

Sequence in context: A297427 A357893 A211115 * A274897 A030736 A227854

Adjacent sequences: A232933 A232934 A232935 * A232937 A232938 A232939

Keyword

nonn

Author

R. H. Hardin, Dec 02 2013

Status

approved