OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-2) + 6*a(n-3) - a(n-4) - 11*a(n-5) - 12*a(n-6) + 5*a(n-7) + 20*a(n-8) + 8*a(n-9) - 8*a(n-10) - 12*a(n-11) + 4*a(n-13) for n>14.
Empirical g.f.: x*(39 + 52*x - 8*x^2 - 242*x^3 - 284*x^4 + 44*x^5 + 513*x^6 + 490*x^7 - 107*x^8 - 432*x^9 - 266*x^10 + 92*x^11 + 112*x^12 - 4*x^13) / ((1 - x)*(1 + x)*(1 - 2*x^3)^2*(1 - x^2 - 2*x^3 + x^5)). - Colin Barker, Dec 05 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..2..2..0....0..1..0..1..1..0....0..1..0..0..2..2....0..1..0..0..2..2
..1..3..3..1..1..3....2..2..0..2..0..0....1..3..1..1..0..0....3..3..0..3..3..1
..2..0..0..3..3..2....3..3..0..0..2..0....2..2..3..3..1..3....1..0..0..1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 20 2014
STATUS
approved