Question 259388
Just write it out, go one line at a time, then move on.
It's pretty straightforward.
{{{ n=0}}},{{{u0=1}}}
{{{n=1}}},{{{u1=4}}}
{{{n=2}}},{{{u2=2*2*u1+2=2*2*4+2=18}}}
{{{n=3}}},{{{u3=3*2*u2+2=3*2*18+2=110}}}
{{{n=4}}},{{{u4=4*2*u3+2=4*2*110+2=882}}}
{{{n=5}}},{{{u5=5*2*u4+2=5*2*882+2=8822}}}