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A008334 Number of distinct primes dividing p-1, where p = n-th prime. 4
0, 1, 1, 2, 2, 2, 1, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 3, 3, 3, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 3, 3, 2, 3, 2, 3, 3, 2, 2, 2, 2, 3, 3, 2, 2, 3, 4, 3, 2, 3, 2, 3, 3, 2, 1, 2, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 4, 3, 2, 3, 2, 2, 3, 3, 3, 2, 2, 3, 2, 3, 3, 4, 3, 2, 3, 3, 2, 3, 3, 4, 2, 2, 2, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

This is omega(p-1), i.e. A001221(A006093(n)). For Omega(p-1)=A001222(A006093(n)), see A023508. - Lekraj Beedassy, Oct 08 2004

Primes counted without multiplicity. - Harvey P. Dale, May 05 2018

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

MAPLE

for i from 1 to 500 do if isprime(i) then print(nops(factorset(i-1))); fi; od;

MATHEMATICA

PrimeNu[#]&/@(Prime[Range[100]]-1) (* Harvey P. Dale, May 05 2018 *)

CROSSREFS

Sequence in context: A097195 A274138 A179301 * A116858 A182134 A189684

Adjacent sequences:  A008331 A008332 A008333 * A008335 A008336 A008337

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Definition clarified by Harvey P. Dale, May 05 2018

STATUS

approved

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Last modified September 19 04:25 EDT 2018. Contains 315155 sequences. (Running on oeis4.)