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

Author

Matthew Vandermast, Jun 09 2012

Keywords

• nonn

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

Crossrefs

Cf. A181800, A000005, A212641.

Formula

a(n) = A000005(A181800(n)).