OFFSET
1,1
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).
Empirical g.f.: 2*x*(4 - x - x^2) / (1 - 4*x - x^2 + 2*x^3). - Colin Barker, Sep 14 2018
EXAMPLE
Some solutions for n=4:
1 0 1 0 1 2 0 2 2 1 1 0 0 1 2 0 0 1 0 1
1 2 2 2 2 0 2 1 0 1 2 1 2 1 1 2 1 2 2 1
0 1 0 1 1 2 0 1 2 1 0 0 0 0 2 1 0 1 0 1
0 1 1 2 0 1 0 1 1 0 1 2 2 2 0 0 1 2 0 1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 21 2013
STATUS
approved