OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-2) + a(n-3) + 3*a(n-4) - 2*a(n-5) - 2*a(n-7) for n>10.
Empirical g.f.: 2*x*(114 - 44*x + 152*x^2 - 21*x^3 - 333*x^4 - 98*x^5 - 119*x^6 + 130*x^7 + 32*x^8 + 16*x^9) / ((1 - x)*(1 - x - x^3 - 4*x^4 - 2*x^5 - 2*x^6)). - Colin Barker, Dec 02 2018
EXAMPLE
Some solutions for n=4:
..1..1..1....1..0..2....0..1..1....0..1..1....1..2..1....1..0..2....1..0..1
..0..2..1....1..2..0....2..0..2....2..0..1....0..2..1....1..2..0....2..0..1
..2..0..2....1..0..2....0..2..0....0..2..1....2..0..2....2..0..2....0..2..0
..0..2..0....1..2..0....2..0..2....2..0..2....0..2..0....0..2..0....2..0..1
..1..0..1....1..0..2....1..2..1....0..2..0....1..0..1....2..0..1....0..2..1
..1..0..1....1..2..0....1..1..1....1..1..1....1..1..1....0..1..1....2..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 15 2014
STATUS
approved