OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-1) + 8*a(n-2).
Conjectures from Colin Barker, Feb 14 2019: (Start)
G.f.: x*(4 + 3*x) / (1 - 14*x - 8*x^2).
a(n) = ((7-sqrt(57))^n*(-11+3*sqrt(57)) + (7+sqrt(57))^n*(11+3*sqrt(57))) / (16*sqrt(57)).
(End)
EXAMPLE
Some solutions for n=4:
..0..1..1. .0..1..1. .0..1..0. .0..1..2. .0..0..1. .0..1..0. .0..1..0
..0..2..2. .0..2..1. .0..2..0. .1..0..1. .1..2..2. .1..2..0. .1..2..1
..0..1..0. .0..1..2. .0..1..1. .1..0..2. .1..0..1. .1..1..2. .2..0..2
..1..2..2. .0..1..1. .0..0..1. .2..1..2. .2..2..1. .0..2..0. .0..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 07 2017
STATUS
approved