The sum command sums the expression expr with respect to the dummy variable, varname, between the values start and stop.

For example, sum(i, 1, 20, i^2) evaluates 1^2 + 2^2 + 3^2 + ... + 20^2 and returns 2870.

$\mathrm{MapleTA}:-\mathrm{Builtin}:-\mathrm{sum}\left(i\,1\,20\,i^2\right)$

$2870$

The MapleTA[Builtin][sum] command was introduced in Maple 18.

For more information on Maple 18 changes, see Updates in Maple 18.