Given number:
$$\left(\frac{x}{4}\right)^{n + 1} \frac{\left(4 n\right)!}{n!^{4}}$$
It is a series of species
$$a_{n} \left(c x - x_{0}\right)^{d n}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{n \to \infty} \left|{\frac{a_{n}}{a_{n + 1}}}\right|}{c}$$
In this case
$$a_{n} = \frac{\left(\frac{x}{4}\right)^{n + 1} \left(4 n\right)!}{n!^{4}}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\left|{\frac{\left(\frac{x}{4}\right)^{- n - 2} \left(\frac{x}{4}\right)^{n + 1} \left(4 n\right)!}{n!^{4} \left(4 n + 4\right)!}}\right| \left(n + 1\right)!^{4}\right)$$
Let's take the limitwe find
$$1 = \frac{1}{64 \left|{x}\right|}$$
$$1 = \frac{0.015625}{\left|{x}\right|}$$
False