triprime

A number n with prime factorization n = product_(i = 1)^r p_i^(a_i) is called k-almost prime if it has a sum of exponents sum_(i = 1)^r a_i = k, i.e., when the prime factor (multiprimality) function Ω(n) = k. The set of k-almost primes is denoted P_k. The primes correspond to the "1-almost prime" numbers and the 2-almost prime numbers correspond to semiprimes. Conway et al. (2008) propose calling these numbers primes, biprimes, triprimes, and so on.

Chen's theorem | prime factor | prime number | semiprime | sphenic number