Recent activity by commit_or_quit

​​​Which one of the given options is a possible value of $x$ in the following sequence?\[3,7,15, x, 63,127,255\]$35$$40$$45$$31$

Given the sequence of terms, $\text{AD CG FK JP}$, the next term is$\text{OV}$$\text{OW}$$\text{PV}$$\text{PW}$