Math & Science ⇒ Spacing in Subscripts and Superscripts

[Stirling]

Consider the following example:

Code: Select all

\documentclass{article}

\begin{document}
\[
	\sum_{k = 0}^{n - 1} a^{k} = \frac{1 - a^{n}}{1 - a \phantom{^{n}}}
\]
\[
	\sum_{k \, = \, 0}^{n \, - \, 1} a^{k} = \frac{1 - a^{n}}{1 - a \phantom{^{n}}}
\]
\end{document}

Although the second example does not follow standard spacing conventions, I find it is easier on my tired eyes, so I tend to add the additional spaces when I am writing documents for my own purposes that I do not intend to circulate. Is it possible to set the default spacing in subscripts and superscripts to avoid typing so many thin spaces?