OFFSET
1,1
COMMENTS
Column 1 of A209960.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) + 15*a(n-2) + 6*a(n-3).
Empirical g.f.: x*(71 + 141*x + 54*x^2) / (1 - 6*x - 15*x^2 - 6*x^3). - Colin Barker, Jul 14 2018
EXAMPLE
Some solutions for n=4:
..1..1....0..2....0..1....2..1....2..1....2..1....1..2....1..2....1..2....2..1
..0..0....2..1....2..0....0..2....0..2....0..0....0..2....1..1....0..2....2..2
..2..0....0..1....1..2....1..1....2..1....1..1....2..1....1..1....0..2....1..2
..0..0....0..1....2..0....1..2....0..2....1..0....2..0....1..0....2..2....0..2
..0..0....1..1....0..1....1..1....1..0....2..2....0..1....1..2....0..2....2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 16 2012
STATUS
approved