  When restricted to some non-negative multiplicative function, say f, bounded
on primes and that vanishes on non square-free integers, our result provides us
with an asymptotic for $\sum_{n \le X}f(n)/n$ with error term $O((\log
X)^{\kappa-h-1+\varepsilon})$ (for any positive $\varepsilon>0$) as soon as we
have $\sum_{p\le Q}f(p)(\log p)/p=\kappa\log Q+\eta+O(1/(\log2Q)^h)$ for a
non-negative $\kappa$ and some non-negative integer $h$. The method generalizes
the 1967-approach of Levin and Fainleib and uses a differential equation.
