OFFSET
1,1
COMMENTS
Column 2 of A232589
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) -a(n-2) -a(n-3) +2*a(n-4).
Empirical: G.f.: -2*x*(5-3*x-x^2+2*x^3) / ( -1+4*x-x^2-x^3+2*x^4 ). - R. J. Mathar, Nov 23 2014
EXAMPLE
Some solutions for n=7
..0..1..2....2..1..2....0..1..2....0..1..2....2..1..2....0..1..0....2..1..0
..0..1..2....0..1..2....2..1..0....0..1..0....0..1..0....2..1..2....2..1..2
..0..1..0....2..1..0....0..1..2....2..1..2....2..1..2....2..1..0....0..1..2
..2..1..2....2..1..0....0..1..2....0..1..2....2..1..0....0..1..0....2..1..2
..0..1..0....0..1..0....2..1..2....2..1..0....2..1..0....2..1..2....0..1..0
..2..1..2....2..1..0....0..1..0....0..1..2....0..1..2....2..1..0....0..1..2
..2..1..2....0..1..2....2..1..0....0..1..0....2..1..0....0..1..2....0..1..2
..0..1..0....0..1..0....2..1..0....2..1..0....2..1..0....0..1..2....0..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 26 2013
STATUS
approved