A276294 Number of n X 3 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,1) or (0,-1) and new values introduced in order 0..2.

2, 12, 45, 189, 805, 3437, 14693, 62829, 268677, 1148973, 4913509, 21012333, 89858053, 384272941, 1643321829, 7027574381, 30053031045, 128520116269, 549609131621, 2350372894061, 10051239005445, 42983564779053

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 8*a(n-2) + 4*a(n-3) - 7*a(n-4) + 6*a(n-5) for n>7.

Empirical g.f.: x*(2 - 11*x^2 + 7*x^3 - 3*x^4 + 11*x^5 - 2*x^6) / ((1 - x)*(1 - 5*x + 3*x^2 - x^3 + 6*x^4)). - Colin Barker, Feb 05 2019

Example

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

Crossrefs

Column 3 of A276299.

Sequence in context: A356868 A267344 A275132 * A066258 A123771 A046991

Adjacent sequences: A276291 A276292 A276293 * A276295 A276296 A276297

Keyword

nonn

Author

R. H. Hardin, Aug 28 2016

Status

approved