\documentclass[12pt]{article} \usepackage{amsmath,mathrsfs,bbm} \usepackage{amssymb} \textwidth=4.825in \overfullrule=0pt \thispagestyle{empty} \begin{document} \noindent % % {\bf Alexander Burstein } % % \medskip \noindent % % {\bf A Short Proof for the Number of Permutations Containing Pattern 321 Exactly Once} % % \vskip 5mm \noindent % % % % We give a short proof for J.~Noonan's result on the number of permutations containing pattern 321 exactly once. \end{document} .