OFFSET
1,1
COMMENTS
Column 1 of A209829.
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) - 2*a(n-3).
Empirical g.f.: x*(8 - 7*x - 4*x^2) / ((1 - x)*(1 - 5*x - 2*x^2)). - Colin Barker, Jul 13 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..1....0..1....0..0....0..0....0..0....0..0....0..0....0..0....0..1
..1..1....0..0....0..0....0..0....0..1....0..1....1..1....0..1....0..0....1..0
..1..1....2..2....2..0....1..0....1..0....0..1....1..0....0..0....0..1....1..0
..0..0....2..0....0..0....0..1....0..0....1..0....0..0....0..1....0..0....0..0
..1..0....2..2....2..2....0..0....1..0....1..1....2..2....1..0....1..0....2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 13 2012
STATUS
approved