This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A230039 #20 Sep 08 2022 08:46:06 %S A230039 7,13,17,19,43,47,67,73,97,127,137,139,157,167,193,197,199,223,227, %T A230039 229,269,277,283,307,337,349,353,379,383,397,409,439,463,467,487,503, %U A230039 523,547,557,563,599,607,613,617,643,647,739,773,797,827,853,859,887,929 %N A230039 Primes p such that 2*p+1 is not prime and 2*p+3 is prime. %C A230039 Intersection of A023204 and A053176. - _Felix Fröhlich_, Jan 14 2017 %H A230039 Vincenzo Librandi, <a href="/A230039/b230039.txt">Table of n, a(n) for n = 1..1000</a> %e A230039 43 is in the sequence because 2*43+1=87 (not prime) and 2*43+3=89 (prime). %t A230039 Select[Range[10^5],PrimeQ[#]&& !PrimeQ[2#+1]&& PrimeQ[2#+3]&] %o A230039 (Magma) [p: p in PrimesUpTo(2500)|not IsPrime(2*p+1) and IsPrime(2*p+3)]; %o A230039 (PARI) is(n) = ispseudoprime(n) && !ispseudoprime(2*n+1) && ispseudoprime(2*n+3) \\ _Felix Fröhlich_, Jan 14 2017 %Y A230039 Cf. A005384, A023204, A053176, A126107, A163769, A230117. %K A230039 nonn,easy %O A230039 1,1 %A A230039 _Vincenzo Librandi_, Oct 10 2013