login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A049238 a(n) is the number of divisors of prime(n) - 2. 0
1, 2, 2, 3, 2, 4, 2, 4, 4, 2, 4, 4, 2, 6, 4, 4, 2, 4, 4, 2, 4, 5, 4, 4, 6, 2, 8, 2, 4, 4, 4, 8, 2, 6, 2, 4, 4, 8, 6, 4, 2, 8, 2, 8, 2, 4, 4, 9, 2, 8, 4, 2, 4, 8, 6, 4, 2, 6, 6, 2, 4, 4, 4, 2, 12, 4, 4, 8, 2, 8, 8, 4, 4, 4, 4, 6, 4, 8, 4, 4, 2, 8, 2, 4, 9, 4, 8, 8, 2, 8, 6, 4, 4, 4, 4, 6, 4, 2, 6, 4, 8, 8, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..104.

FORMULA

a(n) = A000005(prime(n) - 2).

EXAMPLE

prime(23)=83, so a(23) = A000005(83-2) = A000005(81) = 5.

MATHEMATICA

DivisorSigma[0, #]&/@(Prime[Range[2, 110]]-2) (* Harvey P. Dale, Jan 11 2019 *)

PROG

(PARI) a(n) = numdiv(prime(n)-2); \\ Michel Marcus, May 14 2018

CROSSREFS

Sequence in context: A326641 A144372 A182861 * A001616 A257599 A218702

Adjacent sequences:  A049235 A049236 A049237 * A049239 A049240 A049241

KEYWORD

nonn

AUTHOR

Labos Elemer

EXTENSIONS

Offset corrected by Jon E. Schoenfield, May 13 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 8 20:32 EDT 2021. Contains 343668 sequences. (Running on oeis4.)