MathDB
A 110

Source:

May 25, 2007
blogsnumber theoryrelatively primeDivisibility Theory

Problem Statement

For each positive integer nn, write the sum ∑m=1n1/m\sum_{m=1}^n 1/m in the form pn/qnp_n/q_n, where pnp_n and qnq_n are relatively prime positive integers. Determine all nn such that 5 does not divide qnq_n.
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