A104483 Number of distinct prime divisors of 33...337 (with n 3s).

1, 1, 2, 3, 1, 3, 3, 2, 2, 2, 3, 3, 4, 4, 3, 4, 3, 3, 4, 5, 4, 4, 4, 4, 4, 5, 3, 4, 2, 4, 4, 5, 4, 4, 4, 8, 2, 2, 2, 3, 5, 4, 6, 6, 1, 5, 3, 4, 5, 4, 5, 8, 4, 2, 5, 5, 5, 2, 4, 4, 6, 4, 2, 4, 3, 4, 6, 3, 6, 9, 4, 7, 5, 3, 5, 7, 3, 6, 5, 6, 4, 7, 4, 5, 3, 5, 4

Offset

0,3

Comments

Number of distinct prime factors of (10^(n + 1) - 1)/3 + 4. - Stefan Steinerberger, Mar 06 2006

Links

Amiram Eldar, Table of n, a(n) for n = 0..199

Formula

a(n) = A001221(A173766(n+1)). - Amiram Eldar, Jan 24 2020

Example

The number of distinct prime divisors of 37 is 1 (prime).
The number of distinct prime divisors of 337 is 1 (prime).
The number of distinct prime divisors of 3337 is 2.

Mathematica

Table[Length[FactorInteger[(10^(n + 1) - 1)/3 + 4]], {n, 1, 50}] (* Stefan Steinerberger, Mar 06 2006 *)

Crossrefs

Cf. A001221, A173766.

Sequence in context: A231633 A039702 A230294 * A080717 A239214 A200181

Adjacent sequences: A104480 A104481 A104482 * A104484 A104485 A104486

Keyword

nonn,base

Author

Parthasarathy Nambi, Apr 18 2005

Extensions

More terms from Stefan Steinerberger, Mar 06 2006

More terms from Amiram Eldar, Jan 24 2020

Status

approved