OFFSET
1,1
COMMENTS
Column 3 of A222444.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 18*a(n-1) - 27*a(n-2).
Empirical g.f.: 3*x*(3 - 5*x) / (1 - 18*x + 27*x^2). - Colin Barker, Mar 15 2018
EXAMPLE
Some solutions for n=3:
..0..2..3....0..1..2....0..2..2....0..2..3....0..0..0....0..2..2....0..0..1
..2..0..0....2..2..0....1..2..2....2..0..0....0..2..2....0..0..2....2..0..2
..2..0..1....2..0..1....3..3..3....2..0..2....0..2..3....1..2..2....3..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 20 2013
STATUS
approved