La série entière $1+\frac{z}{\Gamma (1+i)}+\frac{z^2}{\Gamma (1+2i)}+\frac{z^3}{\Gamma (1+3i)}+...$ possède une frontière naturelle~!

Changgui Zhang

The lacunary series are the most classical examples among all the power series whose circle of convergence constitutes a natural boundary (\cite[§~93-94, p.~372-383]{Di}, \cite[§7.…