

A141198


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


2



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
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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 A231204 A180987
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



