A recurrence system is defined by {pn=qn−1+2qn=pn−1+qn−1\begin{cases} p_n = q_{n-1} + 2 \\ q_n = p_{n-1} + q_{n-1} \end{cases}{pn=qn−1+2qn=pn−1+qn−1 with p0=0,q0=1p_0 = 0, q_0 = 1p0=0,q0=1. Compute q4q_4q4.
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