Given a sequence $u_1,u_2,u_3,\dots$ we define $S_n$ as

$S_n$ is just the sum of the first $n$ terms of the sequence, and is known as the $n^{\text{th}}$ partial sum.

1. Let $u_n=n^2-2n.$ Find $S_4$ for this sequence.

2. Let

   $$\begin{array}{rl}{v}_1& =16\\ v_{n+1}& =\frac{v_n}{2}\end{array}$$

   be a recursively defined sequence. Find $S_5$ for this sequence.