Solution
= Solution
For each permitted part $i\leq e$, its multiplicity contributes the <geometric series> $1+x^i+x^{2i}+\cdots$. Thus the generating function is
$$
\prod_{i=1}^e\frac1{1-x^i}.
$$
The <conjugate partition> bijects diagrams with largest part at most $e$ and diagrams with at most $e$ rows, so the same series counts partitions into at most $e$ parts.