%== .eq ==%
The Pythagorean theorem, $a^2 + b^2 = c^2$,
relates the hypotenuse to the altitude
and base of a right triangle.
Euler’s formula states that
\[
e^{2\pi \sqrt{-1}} = 1
\]
Ain’t that great!
\begin{equation*}
\sum_{k=1}^\infty \frac{1}{n}
\end{equation*}
\begin{equation}
\label{hoho}\hypertarget{hoho}{\sum_{k=1}^\infty \frac{1}{n^2}}
\end{equation}
\begin{equation}
\hypertarget{}{\sum_{k=1}^\infty \frac{1}{n^3}}
\end{equation}