The main recurrence becomes:
    T(n) = &Theta;(n) + 2*T(n/2) + &Theta;(2<sup>2</sup>)
which is really just
    T(n) = &Theta;(n) + 2*T(n/2)
since &Theta;(2<sup>2</sup>) is some constant times 4, which is a constant,
which is a lower-order term than the &Theta;(n) that's already there.