It is a series of the form ζ_K(s) = ∑n=1∞ a(n)/n^s, where K is a number field and a(n) is the number of ideals in K of norm n.
It is a series of the form ζ_K(s) = ∑n=1∞ a(n)/n^s, where K is a number field and a(n) is the number of ideals in K of norm n.