A105973 Number of distinct prime divisors of 88...883 (with n 8's).

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

Offset: 0

Author

Parthasarathy Nambi, Apr 28 2005

Keywords

• nonn
• base

Examples

			The number of distinct prime divisors of 83 is 1 (prime).
The number of distinct prime divisors of 883 is 1 (prime).
The number of distinct prime divisors of 8883 is 3.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 0..201

Crossrefs

Cf. A104660, A104518, A104660.

Programs

Mathematica

Table[PrimeNu[FromDigits[PadLeft[{3},n,8]]],{n,100}] (* Harvey P. Dale, Mar 08 2015 *)

PARI

a(n) = omega((8*10^(n+1)-53)/9); \\ Michel Marcus, Jan 27 2014

Formula

a(n) = A001221(A173811(n+1)). - Michel Marcus, Jan 27 2014