OFFSET
1,3
COMMENTS
Column 2 of A230275.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - a(n-2) - 2*a(n-3).
Conjectures from Colin Barker, Feb 24 2018: (Start)
G.f.: 2*x^3 / ((1 - x)*(1 - 3*x - 2*x^2)).
a(n) = -1/2 + (2^(-2-n)*(-(-5+sqrt(17))*(3+sqrt(17))^n - (3-sqrt(17))^n*(5+sqrt(17)))) / sqrt(17).
(End)
EXAMPLE
All solutions for n=3:
..0..2....0..1
..1..1....2..2
..2..0....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 14 2013
STATUS
approved