OFFSET
1,2
COMMENTS
Column 2 of A231063.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) + a(n-3).
Empirical g.f.: 2*x^2 / (1 - 3*x - x^2 - x^3). - Colin Barker, Feb 24 2018
EXAMPLE
Some solutions for n=4:
..0..1....0..3....0..3....0..1....0..1....0..1....0..1....0..1....0..3....0..1
..1..2....1..2....1..0....3..2....3..2....3..2....3..2....3..2....1..2....1..2
..2..3....0..3....2..3....1..0....2..1....0..3....2..1....2..3....0..1....0..3
..1..0....3..2....1..2....2..3....3..0....1..2....1..0....1..0....3..2....1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 03 2013
STATUS
approved