8. Let the function
$$
f(x)=a_{0}+a_{1} x+a_{2} x^{2}+\cdots+a_{n} x^{n},
$$

where $a_{0}, a_{1}, \cdots, a_{n}$ are non-negative integers. It is known that $f(1)=4$, $f(5)=152$. Then $f(6)=$ $\qquad$