OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) + 3*a(n-2) - 12*a(n-3).
Empirical g.f.: 3*x*(17 + x - 36*x^2) / (1 - 6*x - 3*x^2 + 12*x^3). - Colin Barker, Nov 29 2018
EXAMPLE
Some solutions for n=4:
..1..1....0..0....1..1....1..0....1..2....2..1....0..2....1..2....2..1....0..0
..1..0....1..2....1..1....1..1....0..1....0..1....1..0....2..0....2..0....2..2
..2..0....2..0....1..2....1..1....1..2....2..0....2..0....1..0....0..2....1..0
..0..1....0..2....0..1....1..1....2..0....2..0....1..2....2..1....2..1....2..0
..2..2....2..0....2..2....2..0....1..0....0..2....0..1....2..0....0..0....2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 01 2014
STATUS
approved