Closed form for ∑k≥11(2k−1)a\sum_{k\geq 1}\frac{1}{(2^k-1)^a}

Is there a closed form for
f(a)=∞∑k=11(2k−1)a,f(a)=\sum_{k=1}^\infty\frac{1}{(2^k-1)^a},
where 0