# Dirichlet series of GCD

$\large \sum_{n=1}^\infty \dfrac{\gcd(n,2016)}{n^2}= \dfrac{a}{b}\pi^2$

If the equation above holds true for positive integers $$a$$ and $$b$$, find $$a+b$$.

Clarification:
$$\gcd(m,n)$$ denotes the greatest common divisor of $$m$$ and $$n$$.

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