The Liouville function, denoted by λ(n) and named after Joseph Liouville, is an important function in number theory.
If n is a positive integer, then λ(n) is defined as:
- λ(n) = (-1)Ω(n),
λ is completely multiplicative since Ω(n) is additive. We have Ω(1)=0 and therefore λ(1)=1. The Lioville function satisfies the identity:
- Σd|n λ(d) = 1 if n is a perfect square, and:
- Σd|n λ(d) = 0 otherwise.