A119691 Numbers n which do not divide any 3^x-2, even though each prime factor of n does divide some 3^x-2.

35, 85, 133, 145, 155, 175, 203, 217, 245, 265, 301, 323, 371, 395, 425, 445, 493, 505, 553, 565, 589, 595, 635, 665, 679, 685, 707, 725, 731, 775, 805, 817, 875, 889, 899, 901, 931, 973, 985, 995, 1015, 1043, 1085, 1115, 1141, 1165, 1205, 1211, 1225

Offset: 1

Author

A.K. Devaraj, Jul 23 2007

Keywords

• nonn

Examples

			35 is here because 5 divides 3^3-2 and 7 divides 3^2-2, but 35 divides no 3^x-2.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A123239, A131960.

Programs

PARI

isA123239(n)=if(!isprime(n),return(0));if(n<5,return(1)); my(m=Mod(3,n)); while(m!=1,m*=3;if(m==2,return(0)));1
is(n)=if(n<9||isprime(n),return(0));my(f=factor(n)[,1]);for(i=1,#f,if(isA123239(f[i]),return(0))); my(m=Mod(3,n)); while(m!=1,m*=3;if(m==2,return(0))); 1 \\ Charles R Greathouse IV, Jul 07 2013

Extensions

Edited by Don Reble, Aug 04 2007