OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) + 4*a(n-2) + 25*a(n-3) + 60*a(n-4) - 24*a(n-5) - 72*a(n-6).
Empirical g.f.: x*(1 + 17*x + 49*x^2 + 36*x^3 - 96*x^4 - 72*x^5) / (1 - 6*x - 4*x^2 - 25*x^3 - 60*x^4 + 24*x^5 + 72*x^6). - Colin Barker, Oct 03 2018
EXAMPLE
Some solutions for n=6.
..1..2..1..1..2..2....0..1..1..2..2..2....1..1..2..0..2..2....1..2..0..2..1..1
..2..0..0..0..1..2....0..1..2..2..2..2....1..2..2..1..1..0....2..1..2..1..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 19 2013
STATUS
approved