OFFSET
1,2
COMMENTS
Row 2 of A221755.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 6*a(n-2) + a(n-3) - 4*a(n-4).
Empirical g.f.: x^2*(2 - x - 4*x^2) / (1 - x - 6*x^2 - x^3 + 4*x^4). - Colin Barker, Aug 10 2018
EXAMPLE
Single solution for n=3:
..0..2..1
..1..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 24 2013
STATUS
approved