OFFSET
1,1
COMMENTS
Column 2 of A217457.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..128
FORMULA
Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 6*a(n-3) - 5*a(n-4) + a(n-5) - 17*a(n-6) - 14*a(n-7) - 26*a(n-8) - 4*a(n-9).
Empirical g.f.: x*(3 + 6*x + 15*x^2 - 17*x^3 + 8*x^4 - 43*x^5 - 12*x^6 - 62*x^7 - 12*x^8) / (1 - 3*x - 3*x^2 - 6*x^3 + 5*x^4 - x^5 + 17*x^6 + 14*x^7 + 26*x^8 + 4*x^9). - Colin Barker, Mar 09 2018
EXAMPLE
Some solutions for n=3:
..2..2....0..0....0..0....0..0....1..0....2..2....0..0....1..2....0..0....1..0
..2..1....0..0....0..0....1..0....0..0....0..1....1..0....1..1....2..0....0..0
..1..1....2..1....2..2....0..0....2..0....0..0....2..2....1..2....0..0....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 03 2012
STATUS
approved