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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 1 19:32 EDT 2020. Contains 334762 sequences. (Running on oeis4.)