A141198 a(n) = the number of divisors of n that are each one more than a power of a prime.

0, 1, 1, 2, 1, 3, 0, 3, 2, 3, 0, 5, 0, 2, 2, 3, 1, 5, 0, 5, 1, 1, 0, 7, 1, 2, 2, 4, 0, 6, 0, 4, 2, 2, 1, 7, 0, 2, 1, 6, 0, 5, 0, 3, 3, 1, 0, 8, 0, 4, 2, 3, 0, 6, 1, 5, 1, 1, 0, 10, 0, 2, 2, 4, 2, 4, 0, 4, 1, 4, 0, 10, 0, 2, 2, 3, 0, 4, 0, 7, 2, 2, 0, 9, 2, 1, 1, 4, 0, 9, 0, 2, 1, 1, 1, 9, 0, 3, 3, 6, 0, 5, 0

Offset

1,4

Comments

1 is considered here to be a power of a prime. 0 is not considered here to be a power of a prime.

Links

Diana Mecum, Table of n, a(n) for n = 1..1049

Example

The divisors of 9 are 1,3,9. 1 is one more than 0, not a power of a prime. 3 is one more than 2, a power of a prime. And 9 is one more than 8, a power of a prime. There are therefore 2 such divisors that are each one more than a power of a prime. So a(9)=2.

Crossrefs

Cf. A141197.

Sequence in context: A079055 A122170 A066029 * A239621 A349444 A231204

Adjacent sequences: A141195 A141196 A141197 * A141199 A141200 A141201

Keyword

nonn

Author

Leroy Quet, Jun 12 2008

Extensions

Corrected and extended by Diana L. Mecum, Jul 05 2007

Status

approved