A081764 - OEIS

%I #13 Mar 19 2019 14:49:21

%S 37,457,1297,2557,4357,6481,8689,11953,14401,26497,33931,44101,47521,

%T 47881,90631,141157,157081,165601,206221,225457,304081,366097,384049,

%U 427351,446881,560737,576721,589591,636781,677041,1037857,1046641,1049941,1079569

%N Primes p such that p*(p-2) divides 3^(p-1)-1.

%H Harvey P. Dale, <a href="/A081764/b081764.txt">Table of n, a(n) for n = 1..100</a>

%t Select[Prime[Range[85000]],PowerMod[3,#-1,#(#-2)]==1&]//Quiet (* _Harvey P. Dale_, Mar 19 2019 *)

%o (PARI) lista(nn) = {forprime(p=3, nn, if (! ((3^(p-1)-1) % (p*(p-2))), print1(p, ", ")););}

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Apr 09 2003

%E More terms from _Michel Marcus_, Dec 02 2013