OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) + a(n-4) - 5*a(n-5) - 7*a(n-6) - 3*a(n-7) + 4*a(n-8) + 6*a(n-9) + 2*a(n-10) for n>12.
Empirical g.f.: x*(172 - 210*x - 231*x^2 - 113*x^3 - 350*x^4 + 333*x^5 + 933*x^6 + 792*x^7 - 86*x^8 - 650*x^9 - 324*x^10 - 32*x^11) / ((1 - x)*(1 + x)*(1 - x - x^2)*(1 - x - 3*x^3 - 4*x^4 - 4*x^5 - 2*x^6)). - Colin Barker, Dec 01 2018
EXAMPLE
Some solutions for n=4:
..3..3..3....3..3..3....3..2..3....1..0..1....3..3..3....2..3..3....3..3..2
..3..3..3....3..3..3....3..3..3....1..0..1....2..3..3....3..3..3....2..3..3
..3..3..3....3..2..3....3..3..3....0..1..0....3..3..2....3..3..3....3..3..3
..3..3..2....3..3..3....3..3..3....0..1..0....3..3..3....3..3..3....3..2..3
..2..3..3....3..3..3....3..2..3....1..0..1....3..3..3....3..3..2....3..3..3
..3..2..3....3..3..2....3..3..3....1..0..1....3..3..2....2..3..3....3..3..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 14 2014
STATUS
approved