怎样写排列？

Question

如何写出这样的排列？

Answer 1

考虑使用amsmath的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}

Answer 2

使用amsmath的pmatrix环境：

\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}

另一个解决方案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} 

Answer 3

我发现了一个专门用于编写排列的包。此包可在此站点上找到。https://ctan.org/pkg/permute。我不知道，但它对其他用户有用。

\documentclass[a4paper,12pt]{article}
\usepackage{permute}%%%% <-----https://ctan.org/pkg/permute
\begin{document}
In this case I have used permute package in math-mode:
\[
a=\pmtid
\pmtdo{(\cdots)}
\pmtdo{1{2} 2{3} 3{4} {n-1}{n} {n}{1}}
\pmtvprint[1 2  3 \cdots {n-1} n] 
\]
In text-mode we have:
$a=\pmtid
\pmtdo{(\cdots)}
\pmtdo{1{2} 2{3} 3{4} {n-1}{n} {n}{1}}
\pmtvprint[1 2  3 \cdots {n-1} n]$ similar a smallmatrix option.
\end{document}