A212640 Number of divisors of A181800(n) (n-th powerful number that is the first integer of its prime signature).
1, 3, 4, 5, 6, 9, 7, 12, 8, 15, 16, 9, 18, 20, 10, 21, 24, 27, 11, 24, 25, 28, 36, 12, 27, 30, 32, 45, 13, 30, 35, 48, 36, 54, 36, 14, 33, 40, 60, 40, 63, 42, 15, 36, 45, 72, 64, 44, 72, 48, 75, 16, 39, 50, 84, 81, 49, 80, 48, 81, 54, 90, 17, 42, 55, 96, 108
Offset: 1
Keywords
Examples
A181800(6) = 36 has 9 divisors (1, 2, 3, 4, 6, 9, 12, 18 and 36). Hence, a(6) = 9.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000