A049238 - OEIS

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

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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