OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 7*a(n-1) + 2*a(n-3) - 8*a(n-4) for n>5.
Empirical g.f.: x*(1 + x)*(1 - x - x^2 - 4*x^3) / ((1 - x)*(1 - 6*x - 6*x^2 - 8*x^3)). - Colin Barker, Oct 30 2018
EXAMPLE
Some solutions for n=4:
..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..0
..1..2....0..1....2..0....0..2....1..1....0..2....0..1....0..0....1..0....0..0
..2..0....1..0....0..0....2..1....1..0....1..0....0..2....2..0....0..1....0..1
..1..2....1..0....0..1....2..1....1..2....1..2....1..0....2..0....0..2....0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 20 2014
STATUS
approved