How do we find the following sum---
$\displaystyle\sum_{m=1}^\infty \displaystyle\sum_{n=1}^\infty \frac{mn^2}{2^n(n2^m+m2^n)}$
How do we find the following sum---
$\displaystyle\sum_{m=1}^\infty \displaystyle\sum_{n=1}^\infty \frac{mn^2}{2^n(n2^m+m2^n)}$
Yes. This problem is just a slight variant of the Putnam 1999 A4 problem. You can see the solution here: