OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 7*a(n-1) -10*a(n-2) -8*a(n-3).
Conjectures from Colin Barker, Oct 20 2018: (Start)
G.f.: x*(33 - 106*x - 72*x^2) / ((1 - 4*x)*(1 - 3*x - 2*x^2)).
a(n) = 4^(1+n) + (2^(-1-n)*((3-sqrt(17))^n*(-19+5*sqrt(17)) + (3+sqrt(17))^n*(19+5*sqrt(17)))) / sqrt(17).
(End)
EXAMPLE
Some solutions for n=4:
..2..1....1..1....0..2....1..0....2..1....2..1....1..0....2..2....1..0....2..2
..0..1....2..2....1..1....1..2....0..1....1..0....0..1....0..0....0..1....0..0
..1..0....2..2....1..1....1..2....2..1....1..2....1..0....1..1....2..1....0..0
..1..2....0..0....1..1....0..1....1..2....1..0....2..1....2..0....1..0....1..1
..2..1....0..0....1..1....1..2....1..2....1..2....2..1....1..1....1..0....2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2014
STATUS
approved