$\displaystyle \sum\limits_{k = 1}^\infty$ $\displaystyle 1/[2k(k+1)]$

$\displaystyle \sum\limits_{k = 1}^\infty$ $\displaystyle 3^{k-1}/4^{3k+1}$

find the sum of the series

I got the last one is 61/ (12*64), but doubt the answer, just want to confirm it