OFFSET
1,2
COMMENTS
Column 1 of A209476.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) - a(n-4) + 4*a(n-5) - 3*a(n-6) + 3*a(n-7) + a(n-8) - 2*a(n-9) + a(n-10) - a(n-11).
Empirical g.f.: x*(1 + x + x^2)*(1 - 2*x + 2*x^2 - x^3 + x^4 + x^5 - x^6 + x^7 - x^8) / (1 - 3*x + 2*x^2 + x^4 - 4*x^5 + 3*x^6 - 3*x^7 - x^8 + 2*x^9 - x^10 + x^11). - Colin Barker, Jul 10 2018
EXAMPLE
Some solutions for n=8:
..0....0....1....0....0....0....2....1....0....2....0....1....0....0....2....0
..0....2....1....1....0....0....2....1....0....2....1....1....0....0....0....1
..0....0....1....1....0....1....2....0....1....2....1....0....2....0....2....1
..1....2....1....1....0....1....2....2....1....2....2....0....2....1....0....0
..1....0....0....1....0....0....2....0....1....0....0....0....2....1....0....0
..0....1....0....0....0....1....1....2....0....1....2....0....2....2....1....0
..1....1....1....1....0....1....1....0....1....1....1....0....1....0....1....0
..1....0....1....1....0....1....0....2....1....1....1....0....1....2....0....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 09 2012
STATUS
approved