Find a formula for $a_n$ that satisfies the recursive definition.

$a_n=\{\begin{array}{ccc}0& \text{w}\text{h}\text{e}\text{n}& n=0\\ 2a_{n-1}+n{2}^n& \text{w}\text{h}\text{e}\text{n}& n>0\end{array}$Find a fbrmula for a$,,$

$\text{'}\_)$ r$).$

$($Due $\backslash \{$ar$.20)$

that satisfies the recursive rlefinition.

I tl u'lrerr rr : $0$

$""$ I $2$o$,,-$t $*$ tt$2"$ n$-$lrerr lr $)$ u$.$