OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 42*a(n-3) + 71*a(n-4) + 56*a(n-5) - 192*a(n-6) + 80*a(n-7) + 77*a(n-8) - 64*a(n-9) + 12*a(n-10).
Empirical g.f.: x*(1 + 11*x - 76*x^2 + 80*x^3 + 242*x^4 - 541*x^5 + 201*x^6 + 239*x^7 - 192*x^8 + 36*x^9) / ((1 - x)*(1 - 2*x)*(1 + 2*x)*(1 - 3*x)*(1 - 3*x^2 + x^3)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Nov 15 2018
EXAMPLE
Some solutions for n=6:
..1....2....1....2....0....0....1....1....2....1....2....0....0....2....2....0
..0....1....2....2....2....1....1....0....1....2....2....0....1....2....1....1
..1....1....1....1....1....1....0....1....0....0....1....1....2....1....0....0
..0....0....2....0....2....2....1....2....1....2....1....0....0....0....2....1
..1....1....1....2....0....2....0....0....0....0....0....2....1....1....0....0
..1....0....2....1....1....2....2....2....0....1....0....2....2....1....0....2
..0....2....1....0....0....1....0....1....1....0....0....0....2....0....1....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 26 2014
STATUS
approved