OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-2) - a(n-4) + a(n-5) - a(n-7) + a(n-8) + a(n-11) for n>15.
Empirical g.f.: x*(3 + 3*x - 2*x^2 + 3*x^4 - 2*x^6 + x^7 + 4*x^8 + 3*x^9 - 2*x^11 - x^12 + x^13 + 2*x^14) / ((1 + x)*(1 - x - x^2 + x^3 - x^5 + x^6 - x^8 + x^9 - x^10)). - Colin Barker, Oct 29 2018
EXAMPLE
All solutions for n=4:
..3..2....3..3....3..3....3..2....3..2....3..2
..2..0....2..0....2..2....2..0....2..0....2..0
..3..3....2..0....2..0....3..3....2..0....3..3
..3..2....2..0....2..0....2..2....2..0....2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 15 2014
STATUS
approved