How to write a permutation?
Consider using amsmath
's smallmatrix
:
\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\[
a = \bigl(\begin{smallmatrix}
1 & 2 & 3 & \cdots & n-1 & n \\
2 & 3 & 4 & \cdots & n & 1
\end{smallmatrix}\bigr)
\]
Here is another permutation $a = \bigl(\begin{smallmatrix}
1 & 2 & 3 & \cdots & n-1 & n \\
2 & 3 & 4 & \cdots & n & 1
\end{smallmatrix}\bigr)$ in text mode.
\end{document}
Using amsmath
's pmatrix
environment:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
a =
\begin{pmatrix}
1 & 2 & 3 & \cdots & n-1 & n \\
2 & 3 & 4 & \cdots & n & 1
\end{pmatrix}
\]
\end{document}
Another solution with matrix
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
a =
\left(
\begin{matrix}
1 & 2 & 3 & \cdots & n-1 & n \\
2 & 3 & 4 & \cdots & n & 1
\end{matrix}
\right)
\]
\end{document}