OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 3*a(n-2) - a(n-3) + a(n-4) - a(n-5) for n>6.
Empirical g.f.: x*(1 + 5*x + 9*x^2 - 3*x^3 + x^4 - 3*x^5) / ((1 + x - x^2)*(1 - 2*x - x^3)). - Colin Barker, Oct 04 2018
EXAMPLE
Some solutions for n=7:
..2..0..1..0..2..1..0....2..1..2..1..0..2..1....1..2..1..0..2..0..1
..1..2..1..0..2..1..2....2..1..2..1..0..2..1....1..2..1..0..1..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 22 2013
STATUS
approved