This article defines an arithmetic function or number-theoretic function: a function from the natural numbers to a ring (usually, the ring of integers, rational numbers, real numbers, or complex numbers).
View a complete list of arithmetic functions
The Dedekind psi-function is an arithmetic function that sends any natural number to the number:
where the product is over all primes dividing .
Relation with other arithmetic functions
- Euler phi-function has a similar expression to the Dedekind psi-function, except that the expression is rather than .