[latex]
\sum_{n=1}^{\infty} \ f \ (x_{n},y_{n},z_{n}) \; \; \longrightarrow \; \; \sum_{n=1}^{\infty} (x_{n^{‘}},y_{n^{‘}},z_{n^{‘}})
[/latex]
http://www.ies.co.jp/math/java/misc/sum/sum.html
http://reference.wolfram.com/mathematica/tutorial/SummationOfSeries.html