A105267 - OEIS

A105267

a(n) = the number of divisors of 33...31, with n 3s.

1, 2, 2, 2, 2, 2, 2, 2, 4, 4, 4, 8, 8, 16, 4, 4, 8, 2, 8, 24, 8, 4, 16, 8, 8, 4, 16, 8, 8, 6, 8, 16, 64, 4, 4, 8, 8, 16, 16, 2, 8, 8, 64, 64, 8, 4, 8, 32, 8, 2, 8, 8, 16, 64, 8, 8, 32, 8, 32, 2, 8, 64, 32, 16, 8, 32, 8, 8, 32, 16, 64, 64, 8, 64, 4, 4, 16, 2

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OFFSET

0,2

COMMENTS

The first seven 33...31 numbers are prime, so those terms are 2. - Don Reble, Oct 26 2006

LINKS

Amiram Eldar, Table of n, a(n) for n = 0..203

FORMULA

a(n) = A000005(A033175(n)). - Amiram Eldar, May 13 2020

MATHEMATICA

a[n_] := DivisorSigma[0, (10^(n + 1) - 7)/3]; Array[a, 30, 0] (* Amiram Eldar, May 13 2020 *)

PROG