$($a$)$ Solve the following recurrence relation and give an asymptotic bound for it:

$T(n)={\displaystyle \underset{i=1}{\overset{n-1}{}}}T(i)$

$($b$)$ Use a recursion tree to compute an asymptotic solution for the recurrence

$J(n)=J(\frac{n}{2})+J(\frac{n}{3})+n.$