OFFSET
1,2
COMMENTS
Column 2 of A204084.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) +4*a(n-2) +17*a(n-3) -2*a(n-4) -4*a(n-5) -16*a(n-6)
Empirical: a(n) = 4*round(2^n/7)^2 - Mark van Hoeij, May 14 2013
Empirical g.f.: 4*x^2*(1 - x - 2*x^2 - 4*x^3) / ((1 - x)*(1 - 4*x)*(1 + x + x^2)*(1 + 2*x + 4*x^2)). - Colin Barker, Jun 06 2018
EXAMPLE
Some solutions for n=5:
..0..1....0..0....1..0....1..1....0..0....1..0....0..0....1..0....1..0....0..0
..0..1....1..1....1..0....0..0....1..1....1..0....1..1....1..0....1..0....1..1
..2..1....2..2....0..3....1..0....1..1....1..0....1..1....1..0....3..3....0..2
..1..0....0..0....0..1....1..0....0..0....0..0....0..0....0..0....0..1....0..0
..1..0....1..1....0..1....1..0....1..1....1..1....1..1....1..1....0..1....1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 10 2012
STATUS
approved