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
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
Programs
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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