I've been looking into two very specific forms that are related to the MRB constant$\sum _{n=1}^{\infty } (-1)^n \left(n^{\frac{1}{n}}-1\right)$ cf http://mathworld.wolfram.com/MRBConstant.html.
They are
$\sum _{n=1}^{\infty } (-1)^n \left(n^{\frac{u}{n}}-1\right)$
and
$\sum _{n=1}^{\infty } (-1)^n \left(n^{\frac{u}{n}}-u\right)$.
I've had some minor success as you can see at http://www.mapleprimes.com/posts/104016-A-Very-False-Graph .

