[Tex/LaTex] How to write a permutation

Question

How to write a permutation like this ?

Answer 1

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}