OFFSET
1,1
COMMENTS
Column 6 of A214101.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 18*a(n-1) - 36*a(n-2) + 16*a(n-3).
Empirical g.f.: 7*x*(3 - 2*x)*(1 - 2*x) / (1 - 18*x + 36*x^2 - 16*x^3). - Colin Barker, Jul 22 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0..2..0..2....0..1..2..1..2..0..1....0..1..2..1..2..1..2
..2..0..1..2..0..2..1....2..0..1..0..1..2..0....2..0..1..2..0..2..1
..0..2..0..1..2..0..2....0..2..0..1..0..1..2....1..2..0..1..2..0..2
..1..0..1..2..0..2..0....1..0..1..2..1..2..0....0..1..2..0..1..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 04 2012
STATUS
approved