6.8 Inequalities6.10 Other Series Expansions

§6.9 Continued Fraction

6.9.1 \mathop{E_{1}\/}\nolimits\!\left(z\right)=\cfrac{e^{{-z}}}{z+\cfrac{1}{1+\cfrac{1}{z+\cfrac{2}{1+\cfrac{2}{z+\cfrac{3}{1+\cfrac{3}{z+}}}}}}}\cdots, |\mathop{\mathrm{ph}\/}\nolimits z|<\pi.

See also Cuyt et al. (2008, pp. 287–290).