OFFSET
1,1
COMMENTS
Column 2 of A208322.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 8*a(n-1) + 6*a(n-2) for n>3.
Conjectures from Colin Barker, Jul 02 2018: (Start)
G.f.: x*(2 - 3*x - 3*x^2) / (1 - 8*x - 6*x^2).
a(n) = ((4-sqrt(22))^n*(-5+sqrt(22)) + (4+sqrt(22))^n*(5+sqrt(22))) / (12*sqrt(22)) for n>1.
(End)
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0
..0..1....0..1....1..1....0..1....0..1....1..1....1..1....0..1....0..2....1..2
..1..0....2..0....0..0....0..1....2..1....2..0....1..2....0..0....1..2....0..2
..1..2....1..0....2..0....2..0....0..2....0..1....1..1....2..1....2..1....2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 25 2012
STATUS
approved