OFFSET
1,1
COMMENTS
Column 4 of A204370.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) -6*a(n-4) +4*a(n-6) for n>9.
Empirical g.f.: x*(891 - 1960*x - 1517*x^2 - 1162*x^3 + 4498*x^4 + 3442*x^5 - 1928*x^6 - 1092*x^7 - 200*x^8) / ((1 - x)*(1 - 2*x - 2*x^2)*(1 - 2*x^3)). - Colin Barker, Jun 07 2018
EXAMPLE
Some solutions for n=5:
..0..0..1..1..1..2....0..0..0..0..0..0....0..0..1..1..1..2....0..0..0..0..1..0
..0..0..0..1..1..1....1..1..1..1..1..1....0..0..0..1..1..1....1..1..1..1..1..1
..1..0..0..0..1..1....2..2..2..2..2..2....1..0..0..0..1..1....1..1..1..1..1..1
..1..1..0..0..0..1....1..1..1..1..1..1....1..1..0..0..0..1....0..0..0..0..0..0
..1..1..1..0..0..0....0..0..0..0..0..0....1..1..1..0..0..0....2..2..2..2..2..2
..0..1..1..1..0..0....2..2..2..2..2..2....2..1..1..1..0..0....2..2..2..2..2..2
..2..2..1..1..1..0....2..2..2..2..2..2....2..0..1..1..1..0....0..2..0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 14 2012
STATUS
approved