MathDB
Miklós Schweitzer 1956- Problem 4

Source:

October 9, 2015
college contests

Problem Statement

4. Denoting by a(n)a(n) the greatest prime factor of the positive integer nn, show that
S=n=11na(n)S= \sum_{n=1}^{\infty } \frac{1}{na(n)}
is convergente. (N. 13)