# How change math font size in power?

How can I change the font for power such a way that the power symbol is rendered much smaller than the number 3 in the following formula? I need to sum (necessarily with \displaystyle) was much smaller number of 3.

\pdfoutput=0
\documentclass[fleqn]{article}
\usepackage[T2A]{fontenc}
\usepackage[cp1251]{inputenc}
\usepackage{concmath}
\usepackage{amsmath}

\begin{document}
\thispagestyle{empty}

\begin{displaymath}
3^{\displaystyle \sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}}
\end{displaymath}

\end{document}


which renders as

But it does sum in power too large. How to make, that sum was, for example, is 10 times less than the number 3? Or 5 times less than the number 3? The number 3 to make very large. And sum to make very small. Possibly?

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Welcome to TeX.SX! You may have a look on our starter guide –  texenthusiast May 15 '13 at 12:32
Have you thought of introducing a symbol, $S$, for the sum and writing $3^S$. –  Marc van Dongen May 15 '13 at 13:14

I show your original, followed by two alternatives. The first scales the summation to 20% of the original size. The second scales the 3 to 500% of the original size. The \scaleobj command is part of the scalerel package. It is similar to the \scalebox command of the graphicx package, except that it defaults to math mode, and takes the current math style into account.

\pdfoutput=0
\documentclass[fleqn]{article}
\usepackage[T2A]{fontenc}
\usepackage[cp1251]{inputenc}
\usepackage{concmath}
\usepackage{amsmath}
\usepackage{scalerel}

\begin{document}
\thispagestyle{empty}

\begin{displaymath}
3^{\displaystyle \sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}}
\end{displaymath}

\begin{displaymath}
3^{\scaleobj{.2}{\displaystyle \sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}}}
\end{displaymath}

\begin{displaymath}
\scaleobj{5}{3}^{\displaystyle \sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}}
\end{displaymath}

\end{document}


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You could use parentheses to make more clear what you would like to show:

3^{\left (\displaystyle \sum_{n=0}^{\infty}\frac{(-1)^n}{2^n} \right)}


Or standard in-line style:

3^{\left (\sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}\right )}


or even

3^{\sum_{n=0}^{\infty}\frac{(-1)^n}{2^n}}


This looks much more natural than having a huge 3 and a tiny \displaystyle formula.

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