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

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

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

Example

A181800(6) = 36 has 9 divisors (1, 2, 3, 4, 6, 9, 12, 18 and 36).  Hence, a(6) = 9.

Crossrefs

Cf. A181800, A000005, A212641.

Sequence in context: A249798 A037348 A277898 * A387279 A333694 A364064

Adjacent sequences: A212637 A212638 A212639 * A212641 A212642 A212643

Keyword

nonn

Author

Matthew Vandermast, Jun 09 2012

Status

approved