What is the MathJax code for an index notation (n over k)

Question

What is the MathJax code required to properly format an index notation for Pascal's Pyramid like so: N over K

The cheatsheet here at MetaStackoverflow has not yielded me results.

Answer 1

You can use a simple matrix.

\begin{pmatrix}
   n \\
   k
\end{pmatrix}

This will generate the wanted result.