OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) for n>9.
Empirical: a(n) = 529*3^(n-3) + 673*2^(n-1) + 3635 for n>6.
Empirical g.f.: x*(1388 - 3546*x - 5642*x^2 + 8729*x^3 + 9282*x^4 - 136*x^5 - 2310*x^6 - 441*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 13 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..0....1..2..2..0....1..0..1..2....0..2..2..2....1..2..2..2
..1..1..1..0....2..2..2..0....2..0..0..0....1..2..1..0....2..2..2..2
..2..1..1..0....2..2..2..0....2..0..0..0....1..2..1..1....1..1..1..1
..2..1..1..1....2..2..2..0....2..0..0..0....0..1..0..1....2..2..2..2
..1..0..0..1....0..0..0..1....2..0..0..2....0..1..0..2....0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 01 2015
STATUS
approved