Tenemos la indeterminación de tipo
oo/oo,
tal que el límite para el numerador es
$$\lim_{n \to \infty} 4^{\log{\left(n \right)}} = \infty$$
y el límite para el denominador es
$$\lim_{n \to \infty} \frac{1}{\operatorname{atan}{\left(\frac{\pi}{n} \right)}} = \infty$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{n \to \infty}\left(4^{\log{\left(n \right)}} \operatorname{atan}{\left(\frac{\pi}{n} \right)}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{\frac{d}{d n} 4^{\log{\left(n \right)}}}{\frac{d}{d n} \frac{1}{\operatorname{atan}{\left(\frac{\pi}{n} \right)}}}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{4^{\log{\left(n \right)}} n \left(1 + \frac{\pi^{2}}{n^{2}}\right) \log{\left(4 \right)} \operatorname{atan}^{2}{\left(\frac{\pi}{n} \right)}}{\pi}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{4^{\log{\left(n \right)}} n \log{\left(4 \right)} \operatorname{atan}^{2}{\left(\frac{\pi}{n} \right)}}{\pi}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{\frac{d}{d n} \frac{4^{\log{\left(n \right)}} n \log{\left(4 \right)}}{\pi}}{\frac{d}{d n} \frac{1}{\operatorname{atan}^{2}{\left(\frac{\pi}{n} \right)}}}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{n^{2} \left(1 + \frac{\pi^{2}}{n^{2}}\right) \left(\frac{4^{\log{\left(n \right)}} \log{\left(4 \right)}}{\pi} + \frac{4^{\log{\left(n \right)}} \log{\left(4 \right)}^{2}}{\pi}\right) \operatorname{atan}^{3}{\left(\frac{\pi}{n} \right)}}{2 \pi}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{n^{2} \left(\frac{2 \cdot 4^{\log{\left(n \right)}} \log{\left(2 \right)}}{\pi} + \frac{4 \cdot 4^{\log{\left(n \right)}} \log{\left(2 \right)}^{2}}{\pi}\right) \operatorname{atan}^{3}{\left(\frac{\pi}{n} \right)}}{2 \pi}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{n^{2} \left(\frac{2 \cdot 4^{\log{\left(n \right)}} \log{\left(2 \right)}}{\pi} + \frac{4 \cdot 4^{\log{\left(n \right)}} \log{\left(2 \right)}^{2}}{\pi}\right) \operatorname{atan}^{3}{\left(\frac{\pi}{n} \right)}}{2 \pi}\right)$$
=
$$\infty$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 2 vez (veces)