# Sandeep's Harmonic Sums

Algebra Level 3

For each positive integer $n$, let $H_n = \frac{1}{1} + \frac{1}{2} + \cdots + \frac{1}{n}.$ If $\sum_{n=4}^{\infty} \frac{1}{nH_nH_{n-1}} = \frac{a}{b}$ for relatively prime positive integers $a$ and $b$, find $a+b$.

This problem is shared by Sandeep S.

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