The binomial series gives a meromorphic continuation of any series of the form $\sum_{n=N}^\infty f(n)^{-s}$ for some polynomial $f(x) = x^r \prod_{k=1}^d (x-a_k)$
$$f(n)^{-s} = n^{-(d+r)s} \prod_{k=1}^d (1-a_kn^{-1})^{-s} = n^{-(d+r)s} \prod_{k=1}^d \left(\sum_{m=0}^\infty {-s \choose m} (-a_k)^m n^{-m}\right) \\= \sum_{l=0}^\infty h_l(s) n^{-s(d+r)-l}$$ $$\sum_{n=N}^\infty f(n)^{-s} = \sum_{l=0}^\infty h_l(s) (\zeta(s(d+r)+l)-\sum_{n=1}^{N-1} n^{-s(d+r)-l})$$ Where for $N > \max_k \frac{1}{|a_k|}$ the last series converges locally uniformly (away from the poles) for every $s$