be the zeta function associated with the principal Delaunay-Voronoi cone.
A general theory asserts that ζ(s) has an analytic continuation which is
holomorphic in the whole complex plane except possible poles at s = 3∕2,
s = 1 and s = 1∕2. In this paper, we shall compute the values of ζ(s) at
non-positive integers. It is not surprising to see that these values are rational
numbers and can be expressed explicitly in terms of Bernoulli numbers;
i.e.