Find the 4th\displaystyle {4}^{{{t}{h}}} term of the recursive sequence {a1=11an=17(an1+4)\displaystyle {\left\lbrace\begin{array}{c} {a}_{{1}}={11}\\{a}_{{n}}={17}{\left({a}_{{{n}-{1}}}+{4}\right)}\end{array}\right.}

a4=\displaystyle {a}_{{4}}=