OFFSET
1,1
COMMENTS
Column 2 of A204685.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-1) +14*a(n-2) -124*a(n-3) -6*a(n-4) +90*a(n-5) -27*a(n-6) for n>8.
Empirical g.f.: x*(2 - 13*x - 79*x^2 + 3*x^3 + 140*x^4 - 57*x^5 - 21*x^6 + 9*x^7) / ((1 + x)*(1 + 3*x)*(1 - 3*x + x^2)*(1 - 15*x + 9*x^2)). - Colin Barker, Feb 23 2018
EXAMPLE
Some solutions for n=5:
..0..1....0..0....0..1....0..0....0..0....0..0....0..0....0..0....0..1....0..0
..1..0....1..0....1..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0
..0..0....0..1....0..0....1..2....1..2....1..1....1..1....1..2....1..0....1..1
..0..1....1..0....2..1....0..1....1..3....2..3....0..1....2..1....1..0....1..2
..1..0....0..1....0..2....0..0....2..0....3..0....1..2....1..0....2..3....2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 18 2012
STATUS
approved