OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) - a(n-5) - a(n-6) + a(n-7) + 2*a(n-8) + a(n-10) for n>12.
Empirical g.f.: x*(2 + 5*x - 4*x^3 - 4*x^4 + x^5 + 8*x^6 + 8*x^7 + 11*x^8 + x^9 + 3*x^10 - 3*x^11) / ((1 + x)*(1 - x - x^2 - x^3 + 2*x^4 - x^5 + 2*x^6 - 3*x^7 + x^8 - x^9)). - Colin Barker, Oct 29 2018
EXAMPLE
Some solutions for n=4:
..3..3..2..2....2..2..3..3....2..2..3..3....2..2..3..3....2..2..3..3
..2..1..3..1....3..1..2..1....0..0..0..2....3..1..0..2....0..0..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 18 2014
STATUS
approved