Answer
$P'_n(a)=f'(a) ; P''_n(a)=f''(a) ; P^{n}_{n}(a)=f^{n}(a)$
Work Step by Step
The Taylor series for $f(x)$ at $x=a$ is as follows:
$P_n(x)=\Sigma_{n=0}^{\infty} \dfrac{f^{k}(a)}{k!}(x-a)^k=f(a)+f'(a)(x-a)+.....+\dfrac{f^{n}(a)}{n!}(x-a)^n$
This can be re-written as: $P'_n(x)=\Sigma_{n=0}^{\infty} \dfrac{f^{k}(a)}{k!}(x-a)^k=f'(a)+2(x-a) \dfrac{f^{n}(a)}{2!}(x-a)^n+....+n \dfrac{(x-a)^{n-1} f^n(a)}{n!}$
$\implies P^{n}_n(x)=(\dfrac{f^n}{n!}) [n(n-1)(n-2).....1]$
Thus, we have the result: $P'_n(a)=f'(a) ; P''_n(a)=f''(a) ; P^{n}_{n}(a)=f^{n}(a)$