# Right curly brace at the end of an equation

I'm trying to write this equation:

I'm facing problem with the curly brace.

I tried using \right

$$2 \uparrow \uparrow k \stackrel{\text{def}} = \left.2^{2^{2^{.^{.^{.^{{2}}}}}}}\right\}$$

which isn't what we want.

and the same result using \bigg :

$$2 \uparrow \uparrow k \stackrel{\text{def}}= 2^{2^{2^{.^{.^{.^{{2}}}}}}}\bigg\}.$$

• Please show the code you tried (complete, short, compilable) and describe exact the problem that occurs. Mar 13, 2016 at 21:47

One way to achieve right curly braces is:

\documentclass{article}
\usepackage{array}

\begin{document}
$\left.\begin{array}{c} 2\uparrow\uparrow k = 2^{2^{2^{2^2}}} \end{array}\right\}$
\end{document}

Raise a \Big brace:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$2 \mathbin{\uparrow\uparrow} k \overset{\mathrm{def}}{=} 2^{2^{2^{\cdot^{\cdot^{\cdot^{2}}}}}} \raisebox{\depth}{\Bigr\}\scriptstyle k}$

\end{document}

A solution with blkarray, yhmath (for its \adots command) and the \upuparrows symbol from amssymb:

\documentclass[a4paper]{article}
\usepackage{mathtools, amssymb, yhmath, blkarray}
\newcommand\eqdef{\ensuremath{\stackrel{\text{def}}{ = }}}

\begin{document}

$2\upuparrows k\eqdef \raisebox{.15\height}{ \begin{blockarray}{@{}c<{\mskip-4mu}\Right{\}}{\scriptstyle k }} 2^{2^{2^{\adots^{\raisebox{-1.25\height}{\scriptscriptstyle 2 }}}}} \end{blockarray} }$%

\end{document}