OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 8*a(n-2) + 4*a(n-3) - 7*a(n-4) + 6*a(n-5) for n>7.
Empirical g.f.: x*(2 - 11*x^2 + 7*x^3 - 3*x^4 + 11*x^5 - 2*x^6) / ((1 - x)*(1 - 5*x + 3*x^2 - x^3 + 6*x^4)). - Colin Barker, Feb 05 2019
EXAMPLE
Some solutions for n=4:
..0..1..2. .0..1..2. .0..1..2. .0..1..2. .0..1..0. .0..1..0. .0..1..2
..2..1..2. .2..1..2. .2..1..0. .0..1..2. .2..1..0. .2..1..2. .0..1..2
..2..1..2. .0..1..2. .0..1..2. .0..1..0. .0..1..0. .2..1..2. .2..1..0
..0..1..2. .2..0..2. .2..0..2. .0..1..2. .0..1..0. .2..1..0. .0..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 28 2016
STATUS
approved