OFFSET
1,2
COMMENTS
Column 1 of A196430.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4).
Empirical: G.f. -x*(1+x)^2 / ( -1+x+x^2+3*x^3+x^4 ). - R. J. Mathar, Jul 25 2012
EXAMPLE
All solutions for n=3:
..0....1....0....0....1
..0....0....2....0....0
..0....0....0....1....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 02 2011
STATUS
approved