<s>[INST] Show that:$\sum\limits_{n=1}^{\infty}{n\over (4n^2-1)(16n^2-1)}={1\over 12}(1-\ln{2})$ Show that
$$\sum_{n=1}^{\infty}{n\over (4n^2-1)(16n^2-1)}={1\over 12}(1-\ln{2})$$
My try:
We split into partial decomposition 
$$n={A\over 2n-1}+{B\over 2n+1}+{C\over 4n-1}+{D\over 4n+1}$$
Setting $n={1\over 2}$, ${-1\over2}$ we have $A={1\over3}$ and $B={-1\over 3}$
Finding C and D is a bit tedious 
I wonder what is the closed form for
$$\sum_{n=1}^{\infty}{1\over an+b}=F(a,b)?$$
This way is not a good approach. Can anyone help me with a better approach to tackle this problem? Thank you.
 [/INST] If we consider
$$ f(x)=\frac{x}{(4x^2-1)(16x^2-1)} $$
we may compute its partial fraction decomposition through the residue theorem:
$$ f(x) = \frac{1}{24}\left(\frac{1}{x-\tfrac{1}{2}}+\frac{1}{x+\tfrac{1}{2}}\right)-\frac{1}{24}\left(\frac{1}{x-\tfrac{1}{4}}+\frac{1}{x+\tfrac{1}{4}}\right)$$
and that leads to:
$$\begin{eqnarray*} \sum_{n\geq 1}f(n) &=& \frac{1}{6}\sum_{n\geq 1}\left(\frac{1}{4n-2}+\frac{1}{4n+2}-\frac{1}{4n-1}-\frac{1}{4n+1}\right) \\&=&\frac{1}{6}\int_{0}^{1}\sum_{n\geq 1}\left(x^{4n-3}+x^{4n+1}-x^{4n-2}-x^{4n}\right)\,dx\\&=&\frac{1}{6}\int_{0}^{1}\frac{x(1-x)(1-x^3)}{1-x^4}\,dx\\&=&\frac{1}{6}\left(\int_{0}^{1}(1-x)\,dx-\int_{0}^{1}\frac{(1-x)^2}{1-x^4}\,dx\right)\\&=&\frac{1}{6}\left(\int_{0}^{1}(1-x)\,dx-\int_{0}^{1}\frac{dx}{x+1}+\frac{1}{2}\int_{0}^{1}\frac{2x}{x^2+1}\,dx\right)\\&=&\frac{1-\log 2}{12}.\end{eqnarray*}$$
</s>