Let f be a primitive positive integral binary quadratic form of discriminant −D, and let r f (n) be the number of representations of n by f up to automorphisms of f . In this article, we give estimates and asymptotics for the quantity n≤x r f (n) β for all β ≥ 0 and uniformly in D = o(x). As a consequence, we get more-precise estimates for the number of integers which can be written as the sum of two powerful numbers.