sigma function

The divisor function of order k is the number theoretic function that gives the sum of kth powers of divisors of a given integer.

Dirichlet divisor problem | distinct prime factors | divisor | divisor product | even divisor function | factor | Fermat's divisor problem | greatest prime factor | Gronwall's theorem | highly composite number | least prime factor | multiperfect number | odd divisor function | Ore's conjecture | perfect number | prime factor | refactorable number | restricted divisor function | Robin's theorem | Silverman constant | sociable numbers | sum of squares function | superabundant number | tau function | totient function | totient valence function | twin peaks | unitary divisor function

college level