A212639 Number of prime factors of A181800(n) (n-th powerful number that is the first integer of its prime signature), counted with multiplicity.
0, 2, 3, 4, 5, 4, 6, 5, 7, 6, 6, 8, 7, 7, 9, 8, 8, 6, 10, 9, 8, 9, 7, 11, 10, 9, 10, 8, 12, 11, 10, 8, 11, 9, 10, 13, 12, 11, 9, 12, 10, 11, 14, 13, 12, 10, 9, 13, 11, 12, 10, 15, 14, 13, 11, 8, 12, 10, 14, 12, 13, 11, 16, 15, 14, 12, 9, 13, 11, 15, 13, 14, 12
Offset: 1
Keywords
Examples
72 (2^3*3^2, or 2*2*2*3*3) has a total of 5 prime factors when repetitions are counted. Since 72 = A181800(8), a(8) = 5.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
- Will Nicholes, List of prime signatures
Comments