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A245909 The number of distinct prime factors of prime(n)^3-1.

%I A245909 #18 May 22 2025 10:21:40
%S A245909 1,2,2,3,4,3,2,3,4,4,4,4,3,4,4,4,3,5,5,4,3,5,4,3,3,3,4,5,4,4,4,4,5,5,
%T A245909 5,5,4,5,3,3,4,5,6,4,4,4,7,4,4,5,4,5,4,4,3,5,5,4,6,5,5,3,5,5,4,4,6,5,
%U A245909 5,5,4,5,5,6,5,3,4,5,4,4,5,5,6,4,5,5,4
%N A245909 The number of distinct prime factors of prime(n)^3-1.
%H A245909 Jens Kruse Andersen, <a href="/A245909/b245909.txt">Table of n, a(n) for n = 1..10000</a>
%F A245909 a(n) = A001221(A030078(n)-1).
%p A245909 A245909 := proc(n)
%p A245909     A001221(ithprime(n)^3-1) ;
%p A245909 end proc:
%t A245909 Table[PrimeNu[Prime[n]^3 - 1], {n, 100}] (* _Vincenzo Librandi_, Aug 06 2014 *)
%o A245909 (PARI) vector(500, n, omega(prime(n)^3-1)) \\ _Derek Orr_, Aug 05 2014
%o A245909 (Python) from sympy import primefactors,prime
%o A245909 def A245909(n):
%o A245909     return len(primefactors(prime(n)**3-1)) # _Chai Wah Wu_, Aug 05 2014
%o A245909 (Magma) [#PrimeDivisors(p^3-1): p in PrimesUpTo(500)]; // _Bruno Berselli_, Aug 06 2014
%K A245909 nonn
%O A245909 1,2
%A A245909 _R. J. Mathar_, Aug 05 2014