OFFSET
1,1
COMMENTS
Column 4 of A217954.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + 6*a(n-5) - 4*a(n-6) + 6*a(n-7) + 4*a(n-8) + 5*a(n-9) + a(n-10) + 3*a(n-11) + 2*a(n-12) + a(n-13).
Empirical g.f.: x*(1 - x + x^2)*(2 + 2*x + x^2)*(2 + 4*x^2 + 4*x^3 + 5*x^4 + 2*x^5 + 3*x^6 + 2*x^7 + x^8) / (1 - 4*x + 6*x^2 - 4*x^3 + x^4 - 6*x^5 + 4*x^6 - 6*x^7 - 4*x^8 - 5*x^9 - x^10 - 3*x^11 - 2*x^12 - x^13). - Colin Barker, Jul 23 2018
EXAMPLE
Some solutions for n=4:
..0....1....2....0....0....0....1....1....1....2....1....3....3....2....2....2
..0....1....3....1....2....2....3....1....3....2....3....3....3....2....1....2
..3....1....3....0....2....1....3....1....0....2....1....0....3....3....1....0
..1....3....2....0....1....0....0....2....0....2....0....0....0....1....1....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 15 2012
STATUS
approved