better posed problem?

[Ralf Stephan]

You wrote 
> of all k-subsets (including the empty subset) of the n-th roots of 1, say n= 0 to 20, 0>= k>=n, how
> many add to zero?
> 
> 1, 1, 2, 2, 4, 2, 10, 2, 16, 8, 34, 2, 100, 2, 130, 38, 256, 2, 1000, 2, 1156 ...
> Superseek comes up empty handed on the rowsum 2,2,4,2,10,...,1156

That may be but I have a hit on 

%I A070894
%S A070894 1,3,1,9,1,15,7,33,1,99,1,129,37,255,1,999,1,1155
%N A070894 Number of subsets of the set of vertices of a regular n-polygon in the plane such that their center of gravity is the center of the polygon.
%C A070894 For a prime p a(p) = 1.
%Y A070894 Cf. A070925.
%O A070894 3,2


ralf