ich habe folgendes Minimalproblem:
\documentclass[12pt]{article}
\usepackage{amsmath,amssymb,amsthm}
\usepackage[ngerman]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{url}
\usepackage{lscape}
\begin{document}
\begin{tabular}{c}
\begin{array}{c} T_k \end{array}
\end{tabular}
\end{document}
