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) - 3*a(n-3).
Empirical g.f.: 3*x*(1 - x) / (1 - 4*x - 6*x^2 + 3*x^3). - Colin Barker, Oct 24 2018
EXAMPLE
Some solutions for n=5:
..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1
..1..2....2..0....1..2....1..0....2..0....1..0....1..0....1..2....1..0....2..0
..2..0....0..1....0..2....0..1....1..2....2..0....0..1....1..2....0..1....2..1
..0..1....0..1....2..1....1..0....2..1....2..1....0..1....2..0....1..2....1..0
..2..0....1..0....1..0....1..0....0..2....1..2....2..0....1..0....0..1....2..1
..0..1....2..1....0..1....0..1....1..0....2..0....0..2....0..1....2..0....1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 07 2014
STATUS
approved