OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 9*a(n-2) for n>4.
Conjectures from Colin Barker, Jan 16 2019: (Start)
G.f.: 12*x^2*(3 - x)*(1 - x) / (1 - 3*x)^2.
a(n) = 8*3^(n-3) * (8*n-3) for n>2.
(End)
EXAMPLE
Some solutions for n=4:
..0..2..1..2. .2..2..2..1. .0..0..2..1. .1..0..1..0. .1..1..0..1
..2..2..2..2. .1..2..1..0. .0..1..0..0. .1..2..0..0. .0..1..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2016
STATUS
approved