Let $\lambda \in (0, \infty)$ be a D5407: Positive real number.

Then \begin{equation} \lim_{N \to \infty} \left( 1 + \frac{\lambda}{N} (e^{i t} - 1) \right)^N = \exp \left( \lambda (e^{i t } - 1) \right) \end{equation}