OFFSET
1,1
COMMENTS
Column 2 of A206206.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-2) + 14*a(n-3) - 3*a(n-4) + a(n-5) + a(n-6) + a(n-7) for n > 9.
Empirical g.f.: 4*x*(120 + 265*x + 392*x^2 - 109*x^3 + 38*x^4 + 41*x^5 + 17*x^6 - 9*x^7 - 3*x^8) / (1 - 3*x^2 - 14*x^3 + 3*x^4 - x^5 - x^6 - x^7). - Colin Barker, Jun 14 2018
EXAMPLE
Some solutions for n=4:
0 0 1 1 2 2 3 0 0 1 0 2 3 0 0 0 3 3 0 1 1
0 0 1 2 2 2 3 3 0 1 2 2 3 3 0 3 3 3 1 1 1
0 1 1 2 2 3 3 3 3 1 2 2 3 3 3 3 3 0 1 1 2
0 1 1 2 3 3 1 3 3 1 1 2 2 3 3 3 0 0 1 2 2
0 0 1 2 3 3 1 1 3 1 1 2 2 2 2 3 0 0 1 2 2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 04 2012
STATUS
approved