A104239 Number of distinct prime factors of 135...(2n-1) (concatenation of n odd numbers).
0, 1, 2, 2, 2, 3, 2, 5, 3, 1, 4, 3, 3, 2, 3, 1, 5, 5, 7, 4, 5, 5, 4, 5, 5, 2, 4, 5, 4, 6, 5, 3, 7, 1, 4, 4, 3, 4, 3, 6, 5, 7, 5, 7, 8, 4, 7, 7, 1, 6
Offset: 1
Examples
The number of distinct prime factors of 13 is 1 (a prime) - the second term in the sequence. The number of distinct prime factors of 135 is 2 - the third term in the sequence. The number of distinct prime factors of 1357 is 2 - the fourth term in the sequence.
Links
- Eric Weisstein's World of Mathematics, Consecutive Number sequences
Programs
-
Mathematica
Join[{0},Table[PrimeNu[FromDigits[Flatten[IntegerDigits/@Range[1,2n+1,2]]]],{n,50}]] (* Harvey P. Dale, Jun 15 2019 *)
Extensions
Corrected and extended by Franklin T. Adams-Watters, Sep 01 2006
Edited by N. J. A. Sloane, May 21 2008 at the suggestion of R. J. Mathar
Comments