OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - a(n-2) + 26*a(n-3) + 16*a(n-4).
Empirical g.f.: 2*x*(5 - 3*x + 34*x^2 + 16*x^3) / (1 - 4*x + x^2 - 26*x^3 - 16*x^4). - Colin Barker, Oct 06 2018
EXAMPLE
Some solutions for n=5:
..0..1..2....0..1..2....2..1..2....2..1..2....2..1..0....2..1..2....0..1..2
..0..1..0....0..1..2....0..1..2....0..1..2....2..1..0....0..1..0....0..1..0
..2..1..2....2..0..1....0..1..2....0..1..2....0..2..1....2..1..2....0..0..1
..0..2..1....1..2..1....0..1..2....2..1..2....1..0..0....0..0..1....1..2..1
..1..0..0....1..0..0....0..1..0....0..1..2....2..1..0....1..2..0....1..0..0
..0..1..2....0..1..2....2..1..2....0..1..0....0..1..2....2..1..0....0..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 02 2013
STATUS
approved