# Thinning Out the Harmonic Series

by G. Hossein Behforooz (Syracuse University)

Mathematics Magazine
October, 1995

Subject classification(s): Series
Applicable Course(s): 3.2 Mainstream Calculus II | 4.11 Advanced Calc I, II, & Real Analysis

The subseries of the harmonic series, $$\sum_{n=1}^{\infty} \frac{1}{n}$$, which consists of all terms with one or more nines in the digits of $$n$$, is a divergent series.

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