imc

Notice this is the term $a_6$ in a recursive sequence, defined recursively as $a_1=3,a_n=2a_{n-1}+1.$ Thus: $$\begin{array}{r}{a}_2=3\cdot 2+1=7.\\ a_3=7\cdot 2+1=15.\\ a_4=15\cdot 2+1=31.\\ a_5=31\cdot 2+1=63.\\ a_6=63\cdot 2+1=\boxed{127}\end{array}$$