A208393 Number of 2 X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

2, 14, 117, 1017, 8838, 76806, 667476, 5800644, 50410008, 438083928, 3807131472, 33085555344, 287527231584, 2498731184736, 21715012867392, 188712490047552, 1639989997584768, 14252194920963456, 123857499353216256

Offset

1,1

Comments

Row 2 of A208392.

Links

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

Formula

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

Conjectures from Colin Barker, Jul 02 2018: (Start)

G.f.: x*(1 + x)*(2 - 4*x - 3*x^2) / (1 - 8*x - 6*x^2).

a(n) = ((4-sqrt(22))^n*(-2+sqrt(22)) + (2+sqrt(22))*(4+sqrt(22))^n) / (8*sqrt(22)) for n>2.

(End)

Example

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

Crossrefs

Cf. A208392.

Sequence in context: A092639 A231615 A277467 * A370671 A361962 A192457

Adjacent sequences: A208390 A208391 A208392 * A208394 A208395 A208396

Keyword

nonn

Author

R. H. Hardin, Feb 25 2012

Status

approved