OFFSET
1,2
COMMENTS
Row 2 of A221245.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) - 54*a(n-3) + 36*a(n-4) for n>5.
Empirical g.f.: x^2*(9 - 31*x + 34*x^2 - 6*x^3) / ((1 - 9*x + 6*x^2)*(1 - 6*x^2)). - Colin Barker, Aug 04 2018
EXAMPLE
Some solutions for n=3:
1 3 1 0 3 0 2 2 0 0 4 2 0 2 0 1 4 1 0 2 2
0 1 0 0 1 2 0 2 0 0 0 0 1 2 1 0 0 0 0 2 0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2013
STATUS
approved