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A119691
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Numbers n which do not divide any 3^x-2, even though each prime factor of n does divide some 3^x-2.
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3
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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
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OFFSET
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1,1
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LINKS
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Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
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EXAMPLE
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35 is here because 5 divides 3^3-2 and 7 divides 3^2-2, but 35 divides no 3^x-2.
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PROG
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(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
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CROSSREFS
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Cf. A123239, A131960.
Sequence in context: A044173 A044554 A156126 * A220007 A115393 A086337
Adjacent sequences: A119688 A119689 A119690 * A119692 A119693 A119694
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KEYWORD
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nonn
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AUTHOR
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A.K. Devaraj, Jul 23 2007
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EXTENSIONS
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Edited by Don Reble, Aug 04 2007
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STATUS
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approved
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