OFFSET
1,1
COMMENTS
Column 2 of A203835.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) -2*a(n-2).
Conjectures from Colin Barker, Jun 05 2018: (Start)
G.f.: 9*x*(25 - 6*x) / (1 - 9*x + 2*x^2).
a(n) = (9*2^(-1-n)*((9-sqrt(73))^n*(-23+3*sqrt(73)) + (9+sqrt(73))^n*(23+3*sqrt(73)))) / sqrt(73).
(End)
EXAMPLE
Some solutions for n=4:
..1..1..2....0..0..2....2..1..0....0..0..2....1..1..2....2..2..2....2..0..1
..0..1..1....0..0..0....0..2..1....0..0..0....1..1..1....1..2..0....0..0..0
..2..0..1....0..1..0....1..0..2....1..0..0....1..1..1....2..2..2....2..0..1
..1..2..0....0..0..1....1..1..0....1..1..0....0..1..2....1..2..1....2..2..0
..0..1..2....0..2..0....2..1..1....0..1..1....2..0..1....2..0..2....2..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2012
STATUS
approved