Published online by Cambridge University Press: 18 May 2009
The nth order polylogarithm Lin(z) is defined for |z| ≦ 1 by
([4, p. 169], cf. [2, §1. 11 (14) and § 1. 11. 1]). The definition can be extended to all values of zin the z-plane cut along the real axis from 1 to ∝ by the formula
[2, §1. 11(3)]. Then Lin(z) is regular in the cut plane, and there is a differential recurrence relation [4, p. 169]
It is convenient to extend the sequence Lin(z) backwards in the manner suggested by (2) and define
Then Li1(z)= – log(l–z), and Lin(z) is a rational function of z for n= 0, – 1, – 2,…. Formula (2) now holds for all integers n.