A082876 Number of prime divisors (counted with multiplicity) of numbers of form a^n + b^n + c^n + ..., where a*b*c* ... is the prime factorization of n.

0, 2, 3, 5, 5, 2, 7, 9, 10, 3, 11, 1, 13, 5, 7, 18, 17, 4, 19, 3, 7, 7, 23, 3, 26, 6, 28, 3, 29, 4, 31, 33, 8, 5, 11, 6, 37, 7, 9, 3, 41, 5, 43, 5, 4, 7, 47, 5, 50, 8, 14, 7, 53, 5, 11, 4, 8, 9, 59, 4, 61, 9, 5, 66, 11, 4, 67, 7, 11, 11, 71, 7, 73, 9, 4

Offset: 1

Author

Jason Earls, May 25 2003

Keywords

• nonn
• more

Comments

A082872(2) and A082872(6) are semiprimes. Where is the next?

Crossrefs

Cf. A001222, A082813, A082814, A082872.

Programs

PARI

a(n) = if(n<2, 0, bigomega(sum(i=1, matsize(f=factor(n))[1], f[i, 1]^n*f[i, 2]))); \\ Jinyuan Wang, Apr 01 2020

Extensions

a(74)-a(75) from Jinyuan Wang, Apr 01 2020