A275402 Number of 3 X n 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,0) or (-1,1) and new values introduced in order 0..2.

3, 16, 84, 444, 2344, 12376, 65344, 345008, 1821600, 9617824, 50780928, 268117056, 1415625088, 7474326400, 39463524352, 208362556160, 1100128676352, 5808544139776, 30668398841856, 161925374911488, 854946069256192

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(3 + 4*x + 2*x^2) / (1 - 4*x - 6*x^2 - 4*x^3). - Colin Barker, Feb 04 2019

Example

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

Crossrefs

Row 3 of A275401.

Sequence in context: A037584 A030983 A069429 * A026131 A026160 A025187

Adjacent sequences: A275399 A275400 A275401 * A275403 A275404 A275405

Keyword

nonn

Author

R. H. Hardin, Jul 26 2016

Status

approved