OFFSET
1,1
COMMENTS
Column 4 of A203984.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) - 270*a(n-3) + 324*a(n-4).
Empirical g.f.: 96*x*(4 - 6*x - 81*x^2 + 108*x^3) / ((1 - 15*x + 18*x^2)*(1 - 18*x^2)). - Colin Barker, Jun 06 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..2..0....0..1..1..1..1....0..1..1..1..1....0..1..2..1..2
..2..2..0..2..0....2..2..2..2..0....2..2..2..2..0....2..1..2..1..2
..0..1..1..2..1....1..0..0..1..1....1..0..1..1..0....0..0..2..0..2
..0..2..0..2..0....2..2..2..2..2....1..0..2..2..2....2..1..1..1..1
..0..1..0..1..0....0..1..0..1..0....1..0..1..0..1....0..0..0..0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 09 2012
STATUS
approved