OFFSET
1,6
FORMULA
Conjecture: a(n) = floor(4*(n+4)/5) - floor(2*(n+4)/3).
Empirical g.f.: -x*(x^7-x^4-x^2-1) / ((x-1)^2*(x^2+x+1)*(x^4+x^3+x^2+x+1)). - Colin Barker, Nov 06 2014
EXAMPLE
For n=6, the multisets {-2,1,1,1,1,1}, {-2,-2,-2,3,3,3}, and no others, sum to 3, so a(6)=2.
CROSSREFS
KEYWORD
nonn
AUTHOR
John W. Layman, Sep 23 2009
STATUS
approved