Prime Factors

Jr., P. Erdős, J. L. Selfridge: A new function associated with the prime factors of ${n \choose k}$ （页面存档备份，存于互联网档案馆）, The art of counting: Selected

（原始内容 (PDF)存档于2016-01-15）.  Zelinsky, Joshua. On the Total Number of Prime Factors of an Odd Perfect Number (PDF). Integers. 3 August 2021, 21 [7 August

Pomerance (2011) Cohen, Graeme L.; Hagis, Peter, jun. On the number of prime factors of n if φ(n) divides n−1. Nieuw Arch. Wiskd. III Series. 1980, 28: 177–185

Ramanujan （1917） Hardy, G. H.; Ramanujan, S., The normal number of prime factors of a number n, Quarterly Journal of Mathematics, 1917, 48: 76–92 [2023-11-06]

a given integer n {\displaystyle n} is tested for divisibility by each prime p i {\displaystyle p_{i}} in order until all its factors are discovered