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) + 9*a(n-3) + 3*a(n-4).
Empirical g.f.: 4*x*(16 + 20*x + 49*x^2 + 15*x^3) / (1 - 2*x - x^2 - 9*x^3 - 3*x^4). - Colin Barker, Nov 05 2018
EXAMPLE
Some solutions for n=7:
3 3 4 0 2 2 3 2 2 3 4 3 4 0 4 0
4 4 1 3 1 1 4 3 4 2 2 0 1 3 2 1
4 4 1 0 1 1 3 4 4 3 4 2 2 2 1 1
4 2 2 2 0 4 4 3 2 3 3 0 0 3 4 2
3 4 0 0 2 2 3 3 1 0 2 1 3 4 4 4
3 3 0 3 0 1 2 3 4 0 4 2 3 3 3 4
2 3 0 0 1 1 0 0 2 2 1 1 0 2 4 4
4 0 3 0 1 2 3 0 1 3 2 4 2 3 4 4
4 0 2 1 1 4 0 3 0 4 1 1 1 0 2 4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 09 2014
STATUS
approved