Definition:Weierstrass Elementary Factor

Definition
Let $n$ be a positive integer.

The $n$th (Weierstrass) elementary factor is the function $E_n:\C\to\C$ defined as:
 * $E_n(z)=\displaystyle\begin{cases}1-z&\text{if }n=0\\(1-z)\exp\left(z+\frac{z^2}2+\cdots+\frac{z^n}n\right)&\text{otherwise}\end{cases}$