Find the matrix $A$ of the linear transformation $$T(f(t)) = \int_{-8}^{6} f(t) dt$$ from $P_3$ to ${\mathbb R}$ with respect to the standard bases for $P_3$ and ${\mathbb R}$.

$A=$ $\left[\Rule{0pt}{1.2em}{0pt}\right.$$\left]\Rule{0pt}{1.2em}{0pt}\right.$