OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) - 18*a(n-2).
Empirical g.f.: 24*x*(2 - 3*x) / (1 - 15*x + 18*x^2). - Colin Barker, Oct 08 2018
EXAMPLE
Some solutions for n=4:
..1..2..1..2..2....0..1..2..1..0....2..1..0..0..0....1..2..1..2..2
..2..2..1..2..2....0..1..0..1..2....2..1..0..1..2....2..2..2..2..2
..2..2..1..2..1....0..1..2..1..0....2..1..0..1..2....2..1..2..1..2
..1..2..1..2..2....2..1..0..1..2....0..0..0..1..2....0..1..0..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 05 2013
STATUS
approved