This is a \(\infty \frac{x^3}{e^x-1}\) with few symbols.

Eq 1,

\[
\begin{equation}
\int_0^\infty \frac{x^3}{e^x-1}\,dx = \frac{\pi^4}{15}
\label{eq:sample}
\end{equation}
\]

Eq 2 without starting with beginning equation tagger,

\[
\Gamma(z) = \int_0^\infty t^{z-1}e^{-t}dt\,.
\]