The sequence $u_n$ is defined by

1. Show that the sequence is periodic and give its period.

2. Find $u_{27}$

3. Find

   $$u_1+u_2+u_3+\dots +u_{300}$$

For part (c), group the terms together in a convenient way.

In the sum, $3+\frac{1}{3}$ appears $150$ times.