A049238 a(n) is the number of divisors of prime(n) - 2.

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

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 A366620

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