How to compute following double series,
$$\sum_{j=1}^{\infty}\sum_{i=1}^{\infty} \cfrac{(-1)^{(i+j)}}{i^2+2nij+j^2} $$
where $n\in \mathbb{N}$.
How to compute following double series,
$$\sum_{j=1}^{\infty}\sum_{i=1}^{\infty} \cfrac{(-1)^{(i+j)}}{i^2+2nij+j^2} $$
where $n\in \mathbb{N}$.