\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
Using the table below, find \(u_8\).
\(n\) 1 2 3 4 5 6 7 8
\(u_n\) 1 3 7 15 31 63 127 255
\(u_8=\)