OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 10*a(n-2) + 4*a(n-3) - 4*a(n-4) for n>6.
Empirical g.f.: 16*x*(1 + 24*x - 15*x^2 - 98*x^3 - 52*x^4 + 40*x^5) / (1 - 3*x - 10*x^2 - 4*x^3 + 4*x^4). - Colin Barker, Jan 31 2019
EXAMPLE
Some solutions for n=5:
..0..1..2..1..0..2. .0..1..2..0..1..2. .0..1..2..1..0..2. .0..1..2..0..1..0
..2..1..2..0..1..0. .0..1..2..0..1..2. .2..1..2..0..1..2. .0..1..2..0..1..2
..2..0..1..2..1..2. .2..0..1..2..1..2. .1..0..1..2..0..2. .2..0..1..2..0..1
..2..0..1..2..0..1. .1..0..1..2..0..1. .1..2..0..2..0..1. .1..2..1..2..0..1
..0..2..0..1..0..1. .0..2..0..1..2..0. .0..2..0..1..2..1. .2..1..0..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 17 2016
STATUS
approved