OFFSET
1,1
COMMENTS
Column 1 of A206128.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 13*a(n-2) - 9*a(n-3) - 50*a(n-4) - 43*a(n-5) + 4*a(n-6) - 4*a(n-8) for n>9.
Empirical g.f.: 2*x*(25 + 35*x - 216*x^2 - 485*x^3 - 325*x^4 + 31*x^5 - 10*x^6 - 32*x^7 - x^8) / ((1 - 8*x^2 - 4*x^3)*(1 - 2*x - 5*x^2 - 3*x^3 + 2*x^4 - x^5)). - Colin Barker, Jun 13 2018
EXAMPLE
Some solutions for n=4:
..1..2....1..1....2..0....0..1....2..0....0..1....2..1....2..1....1..0....1..1
..0..2....0..1....1..2....2..2....2..1....2..1....2..2....0..2....1..2....2..1
..2..0....1..1....0..2....1..0....0..2....0..2....2..0....1..0....1..1....1..1
..0..1....0..1....2..0....2..1....1..0....1..0....2..2....2..1....0..1....1..2
..2..1....1..1....2..1....1..2....2..1....2..1....1..2....1..0....1..1....1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 04 2012
STATUS
approved