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A091180 Primes of the form 3*p - 2 such that p is a prime.

%I A091180 #20 Sep 08 2022 08:45:12
%S A091180 7,13,19,31,37,67,109,127,139,157,181,199,211,307,337,379,409,487,499,
%T A091180 541,571,577,631,751,769,787,811,829,877,919,937,991,1009,1039,1117,
%U A091180 1201,1291,1297,1327,1381,1399,1459,1471,1567,1621,1669,1759,1777,1801
%N A091180 Primes of the form 3*p - 2 such that p is a prime.
%C A091180 Mother primes of order 1. - _Artur Jasinski_, Dec 12 2007
%H A091180 K. D. Bajpai, <a href="/A091180/b091180.txt">Table of n, a(n) for n = 1..10000</a>
%F A091180 a(n) = 3*A088878(n)-2.
%e A091180 From _K. D. Bajpai_, Jun 20 2015: (Start)
%e A091180 a(4) = 31: 3*11 - 2 = 31; A088878(4) = 11.
%e A091180 a(6) = 67: 3*23 - 2 = 67; A088878(6) = 23.
%e A091180 (End)
%p A091180 A091180:= n-> (3*ithprime(n)-2): select(isprime,[seq((A091180(n), n=1..100))]);  # _K. D. Bajpai_, Jun 20 2015
%t A091180 n = 1; a = {}; Do[If[PrimeQ[(Prime[k] + 2n)/(2n + 1)], AppendTo[a, Prime[k]]], {k, 1, 500}]; a (* _Artur Jasinski_, Dec 12 2007 *)
%t A091180 Select[Table[3*Prime[n] - 2,{n, 1000}], PrimeQ] (* _K. D. Bajpai_, Jun 20 2015 *)
%o A091180 (PARI) forprime(p =  1, 1000, k =( 3*p -2); if ( isprime(k), print1(k, ", "))); \\  _K. D. Bajpai_, Jun 20 2015
%o A091180 (Magma) [ k: p in PrimesUpTo(1000) | IsPrime(k)  where k is (3*p-2) ]; // _K. D. Bajpai_, Jun 20 2015
%Y A091180 Cf. A088878, A091179, A091181.
%Y A091180 Cf. A136020.
%K A091180 nonn,easy
%O A091180 1,1
%A A091180 _Ray Chandler_, Dec 27 2003
%E A091180 Name clarified by _Jinyuan Wang_, Aug 06 2021