Definition:Dirichlet Convolution
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Definition
Let $f, g$ be arithmetic functions.
Definition 1
The Dirichlet convolution of $f$ and $g$ is the arithmetic function:
- $\ds \map {\paren {f * g} } n = \sum_{d \mathop \divides n} \map f d \map g {\frac n d}$
where the summation runs over the set of positive divisors $d$ of $n$.
Definition 2
The Dirichlet convolution of $f$ and $g$ is the arithmetic function:
- $\ds \map {\paren {f * g} } n = \sum_{a b \mathop = n} \map f a \map g b$
where the summation runs over all pairs of positive integers $\tuple {a, b}$ with $a b = n$.
Also see
- Results about Dirichlet convolution can be found here.
Generalization
Source of Name
This entry was named for Johann Peter Gustav Lejeune Dirichlet.