OFFSET
1,1
COMMENTS
Column 2 of A209534.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 8*a(n-2) - 8*a(n-3).
Conjectures from Colin Barker, Jul 10 2018: (Start)
G.f.: x*(9 + 16*x - 32*x^2) / ((1 - x)*(1 - 8*x^2)).
a(n) = 3*2^((3*(n - 1))/2 + 3/2) + 1 for n even.
a(n) = 2^((3*(n - 1))/2 + 3) + 1 for n odd.
(End)
EXAMPLE
Some solutions for n=4:
..0..1..2....1..0..1....2..0..2....2..1..0....1..2..1....0..1..0....2..1..0
..1..2..1....2..1..2....0..2..0....1..2..1....2..1..2....1..0..1....1..2..1
..0..1..0....1..2..1....2..0..2....2..1..2....1..0..1....2..1..2....0..1..0
..1..0..1....2..1..2....0..2..0....1..2..1....2..1..2....1..0..1....1..2..1
..0..1..2....1..2..1....2..0..2....0..1..0....1..2..1....2..1..0....0..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 10 2012
STATUS
approved