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A230117 Primes p such that 2*p+1 is prime and 2*p+3 is not prime.

%I A230117 #22 Sep 08 2022 08:46:06
%S A230117 3,11,23,41,83,131,179,191,233,239,251,281,293,359,419,431,443,491,
%T A230117 593,641,653,683,719,761,911,953,1019,1031,1049,1103,1223,1229,1289,
%U A230117 1409,1439,1451,1481,1511,1601,1811,1889,1901,1931,1973,2003,2039,2069,2141
%N A230117 Primes p such that 2*p+1 is prime and 2*p+3 is not prime.
%C A230117 Intersection of A005384 and A163769. - _Felix Fröhlich_, Jan 14 2017
%H A230117 Vincenzo Librandi, <a href="/A230117/b230117.txt">Table of n, a(n) for n = 1..1000</a>
%e A230117 23 is in the sequence because 2*23+1=47 (prime) and 2*23+3=49 (not prime).
%t A230117 Select[Range[10^6],PrimeQ[#]&& PrimeQ[2#+1]&&!PrimeQ[2#+3]&]
%o A230117 (Magma) [p: p in PrimesUpTo(2500)| IsPrime(2*p+1) and not IsPrime(2*p+3)];
%o A230117 (PARI) is(n) = ispseudoprime(n) && ispseudoprime(2*n+1) && !ispseudoprime(2*n+3) \\ _Felix Fröhlich_, Jan 14 2017
%Y A230117 Cf. A005384, A023204, A053176, A126107, A163769, A230039.
%K A230117 nonn,easy
%O A230117 1,1
%A A230117 _Vincenzo Librandi_, Oct 10 2013