The Summand(f) command returns a list containing the summands found in f, sorted by summation nesting level.

$\mathrm{with}\left(\mathrm{Student}\left[\mathrm{Calculus1}\right]\right)\:$

$R≔\mathrm{ApproximateInt}\left(\sin \left(x\right)+3\,x=0..3\,\mathrm{output}=\mathrm{sum}\right)$

$R≔\frac{3\left(\sum _{i=0}^9\left(\sin \left(\frac{3i}{10}+\frac{3}{20}\right)+3\right)\right)}{10}$

$\mathrm{Summand}\left(R\right)$

$\left[\sin \left(\frac{3i}{10}+\frac{3}{20}\right)+3\right]$

$\mathrm{Summand}\left(\mathrm{Sum}\left(\frac{1}{n^2}\,n=1..\mathrm{\infty }\right)\right)$

$\left[\frac{1}{n^2}\right]$

$\mathrm{Summand}\left(\left[\mathrm{Sum}\left(\frac{1}{n}\,n\right)\,\mathrm{Sum}\left(\frac{1}{k^2}\,k\right)\,\mathrm{Sum}\left(\mathrm{Sum}\left(\frac{j}{k^3}\,j=1..10\right)\,k=1..10\right)\right]\right)$

$\left[\frac{j}{k^3}\,\frac{1}{n}\,\frac{1}{k^2}\,\sum _{j=1}^{10}\frac{j}{k^3}\right]$

$\mathrm{Summand}\left(\right)$

$\left[\frac{j}{k^3}\right]$