Definition:Divisor Sum Function/Also known as

Divisor Sum Function: Also known as

The divisor sum function is usually referred to as the sigma function, and denoted $\map \sigma n$.

However, there is more than one function which bears that name, so on $\mathsf{Pr} \infty \mathsf{fWiki}$ we use the more explicit name divisor sum function.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): Glossary
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $12$
• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): sigma function or $\sigma$ function: 1.
• 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {B}.2$: More about Numbers: Irrationals, Perfect Numbers and Mersenne Primes
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): Glossary
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $12$
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): sigma function
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): sigma function