MATLAB : Evaluate the following series $$

$u_n$ in which $u_n$ is not known explicitly but is given in terms of a recurrence relation. You should stop the summation when

$u_{n+1}=(u_{n-1}{)}^2+(u_n{)}^2$ with $u_1=0\mathrm{.}5,u_2=0\mathrm{.}6$