OFFSET
1,1
COMMENTS
Column 2 of A209897
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 8*a(n-1) +4*a(n-2) -16*a(n-3).
Empirical G.f.: 2*x*(17+4*x-36*x^2)/(1-8*x-4*x^2+16*x^3). [Colin Barker, Mar 15 2012]
EXAMPLE
Some solutions for n=4
..0..0..0....0..0..0....0..0..0....0..1..2....0..0..0....0..1..1....0..1..0
..0..1..0....0..1..0....0..1..0....0..1..2....0..1..1....0..0..0....0..0..1
..0..0..0....1..0..0....0..0..1....0..1..1....0..0..1....0..1..0....1..0..0
..2..2..2....0..0..2....1..1..0....1..0..0....0..1..0....0..1..1....0..1..0
..0..2..0....1..0..2....1..0..1....0..0..2....1..0..0....0..0..1....0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 14 2012
STATUS
approved