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%I #17 Oct 30 2019 15:24:37
%S 2,11,41,59,83,107,131,179,227,251,347,419,443,467,491,563,587,659,
%T 683,761,827,947,971,1019,1091,1163,1181,1187,1223,1259,1283,1289,
%U 1307,1427,1451,1499,1511,1523,1571,1583,1619,1667,1787,1811,1871,1877
%N Terms of A123239 which are 2 mod 3.
%C Terms of A123239 which are also primes in Z(w) where w = (-1+sqrt(-3))/2 is a cube root of unity.
%H Charles R Greathouse IV, <a href="/A168367/b168367.txt">Table of n, a(n) for n = 1..10000</a>
%t MangammalQ[p_] := Block[{k = 3}, While[k > 2, k = Mod[3 k, p]]; k != 2];
%t A168367 = Select[Prime[Range[290]], MangammalQ[#] && Mod[#, 3] == 2 &] (* _Ray Chandler_, Jul 21 2011 *)
%o (PARI) is(n)=if(n<9, return(n==2)); if(n%6!=5 || !isprime(n) || znorder(Mod(3, n)) == n-1, return(0)); my(m=Mod(3, n)); while(m!=1, m*=3; if(m==2, return(0))); 1 \\ _Charles R Greathouse IV_, May 21 2017
%Y Cf. A003627, A123239, A168325.
%K nonn
%O 1,1
%A _A.K. Devaraj_, Nov 23 2009, Nov 25 2009
%E Extended by _Ray Chandler_, Jul 21 2011
%E Definition simplified by _Charles R Greathouse IV_, May 21 2017
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