%binom.tex
\documentclass[a4paper,12pt]{report}
\usepackage{fullpage}
\usepackage[ngerman]{babel}
\usepackage{amsmath}

\newcommand{\N}{\mathbb{N}}

\begin{document}\Large
\noindent Der Binomialkoeffizient ...
\begin{displaymath}
\left(
\begin{array}{c}
	n\\
	k
\end{array}
\right)
\quad=\quad
\left(\!\! 
\begin{array}{c}
	n\\
	k
\end{array}
\!\!\right)
\quad = \quad
\left(
\begin{matrix}
	n\\
	k
\end{matrix}
\right)
\quad = \quad
\begin{pmatrix}
	n\\
	k
\end{pmatrix}
\quad = \quad
\binom{n}{k}
\end{displaymath}
\end{document}