Upgrading from:

DiscreteMath`RSolve`

The functionality is now available in built-in Mathematica kernel functions RSolve, ZTransform, and Sum.
The built-in kernel function SeriesCoefficient now contains the functionality for SeriesTerm.

Compute the generating function of the sequence of squares of integers using Sum:

Version 5.2 << DiscreteMath`RSolve`;
PowerSum[n^2, {x, n}]

Compute the general term in the series expansion of , using SeriesCoefficient:

Version 5.2 << DiscreteMath`RSolve`;
SeriesTerm[ⅇ^x, {x, 0, n}]

ExponentialPowerSum, HSolve, ISolve, PartialFractions, and PowerSum were available in previous versions of Mathematica and are now available on the web at library.wolfram.com/infocenter/MathSource/6825.