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 A230225 #10 Sep 08 2022 08:46:06
%S A230225 31,37,59,61,71,79,101,103,107,109,149,151,163,181,211,241,257,263,
%T A230225 271,311,313,317,331,347,367,373,389,401,421,433,449,457,461,479,499,
%U A230225 521,541,569,571,577,587,601,619,631,661,673,677,691,701,709,727,733,751
%N A230225 Primes p such that 2*p+1 and 2*p+3 are not prime.
%H A230225 Vincenzo Librandi, <a href="/A230225/b230225.txt">Table of n, a(n) for n = 1..1000</a>
%e A230225 31 is in the sequence because 2*31+1=63 and 2*31+3=65 are not prime.
%t A230225 Select[Range[10^3], PrimeQ[#]&&!PrimeQ[2 # + 1]&&!PrimeQ[2 # + 3]&]
%t A230225 Select[Prime[Range[200]],NoneTrue[2#+{1,3},PrimeQ]&] (* _Harvey P. Dale_, Sep 19 2021 *)
%o A230225 (Magma) [p: p in PrimesUpTo(2500)|not IsPrime(2*p+1) and not IsPrime(2*p+3)];
%Y A230225 Cf. A005384, A023204, A053176, A089531, A126107, A163769, A230039, A230117.
%K A230225 nonn,easy
%O A230225 1,1
%A A230225 _Vincenzo Librandi_, Oct 12 2013