OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) + 12*a(n-2) + 39*a(n-3).
Empirical g.f.: 3*x*(1 + 11*x + 13*x^2) / (1 - 6*x - 12*x^2 - 39*x^3). - Colin Barker, Oct 05 2018
EXAMPLE
Some solutions for n=6:
..1..0....1..1....0..2....0..2....1..1....0..1....1..0....0..1....0..2....1..1
..2..1....2..2....1..2....2..1....2..0....1..2....2..1....2..2....1..0....0..2
..1..0....1..2....1..2....1..0....2..2....1..0....2..2....2..2....0..0....0..2
..0..0....1..2....0..1....1..1....2..2....2..2....2..2....1..0....0..1....1..1
..0..1....2..1....1..2....2..0....1..2....0..2....1..2....0..2....1..2....2..1
..2..2....0..1....0..0....1..0....0..1....2..1....1..1....0..1....2..1....1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 24 2013
STATUS
approved