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Primes p such that p-1 has 3 distinct prime factors.
2

%I #21 Jun 29 2022 02:57:44

%S 31,43,61,67,71,79,103,127,131,139,151,157,181,191,199,223,229,239,

%T 241,271,277,281,283,307,311,313,337,349,367,373,379,397,409,419,431,

%U 439,443,457,461,491,499,521,523,541,599,601,607,613,617,619,643,647,659

%N Primes p such that p-1 has 3 distinct prime factors.

%H Amiram Eldar, <a href="/A067467/b067467.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Prime[Range[150]],PrimeNu[#-1]==3&] (* _Harvey P. Dale_, Mar 13 2022 *)

%o (PARI) lista(nn) = {forprime(p=1, nn, if (omega(p-1) == 3, print1(p, ", ")););} \\ _Michel Marcus_, Nov 22 2013

%Y Cf. A006093, A008334.

%K nonn

%O 1,1

%A _Benoit Cloitre_, Feb 23 2002