Mathematical notation in a Franklin project are supported out of the box with KaTeX.
Note: Use the online reference of Supported TeX Functions.
Examples
Inline math: \( \varphi = \dfrac{1+\sqrt5}{2}= 1.6180339887…\)
Block math:
\[ \varphi = 1+\frac{1} {1+\frac{1} {1+\frac{1} {1+\cdots} } } \]