The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A023582 Number of distinct prime divisors of 2*prime(n)-1. 2
 1, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 1, 2, 2, 3, 2, 1, 2, 2, 2, 1, 3, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 1, 2, 2, 3, 3, 1, 2, 3, 2, 1, 1, 2, 2, 1, 3, 2, 2, 2, 2, 3, 2, 1, 2, 3, 2, 3, 1, 2, 1, 2, 1, 1, 3, 2, 3, 2, 1, 2, 1, 3, 3, 2, 2, 2, 2, 1, 3, 2, 1, 3, 3, 2, 2, 2, 2, 3, 2, 2, 1, 3, 2, 2, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS G. C. Greubel, Table of n, a(n) for n = 1..5000 FORMULA a(n) = A001221(A076274(n)). - Michel Marcus, Oct 01 2013 MAPLE seq(nops(numtheory:-factorset(2*ithprime(n)-1)), n=1..120); # Muniru A Asiru, Apr 29 2019 MATHEMATICA PrimeNu[2*Prime[Range[100]]-1] (* Harvey P. Dale, Jan 25 2015 *) PROG (PARI) a(n) = omega(2*prime(n)-1); \\ Michel Marcus, Oct 01 2013 CROSSREFS Sequence in context: A206828 A327164 A094781 * A306717 A195969 A023518 Adjacent sequences:  A023579 A023580 A023581 * A023583 A023584 A023585 KEYWORD nonn AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 23 18:45 EDT 2021. Contains 345402 sequences. (Running on oeis4.)