[math-fun] Re: better posed problem?

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