§27.20 Methods of Computation: Other Number-Theoretic Functions
To calculate a multiplicative function it suffices to determine its values at the prime powers and then use
(27.3.2). For a completely multiplicative function we use the values at the primes together with
(27.3.10).
A recursion formula obtained by differentiating (27.14.18) can be used to
calculate Ramanujan’s function
, and the values can be checked by the
congruence (27.14.20). See Lehmer (1943, pp. 483–492).