OFFSET
1,1
COMMENTS
Column 2 of A206169.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 217*a(n-2) - 33*a(n-3) - 1320*a(n-4) - 432*a(n-5) + 1152*a(n-6) for n>7.
Empirical g.f.: x*(85 + 985*x - 2373*x^2 - 8345*x^3 + 3536*x^4 + 10032*x^5 - 2688*x^6) / ((1 - x - 4*x^2)*(1 - 213*x^2 - 180*x^3 + 288*x^4)). - Colin Barker, Jun 13 2018
EXAMPLE
Some solutions for n=4:
..0..1..0....0..0..0....0..0..0....0..1..0....0..1..0....0..0..1....0..1..0
..0..0..2....0..1..0....0..0..0....1..0..1....1..0..1....1..0..0....0..0..0
..3..3..1....3..1..0....2..3..2....0..2..0....3..1..3....1..2..3....1..1..1
..1..3..3....0..3..1....3..1..3....1..3..3....2..2..2....2..2..2....0..1..3
..0..2..0....2..3..2....1..3..1....3..0..3....1..2..3....1..1..0....2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 04 2012
STATUS
approved