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 A023213 #24 Sep 08 2022 08:44:47 %S A023213 2,5,7,11,17,19,31,37,41,47,59,67,89,107,109,149,151,157,179,181,227, %T A023213 229,241,257,271,307,331,349,359,367,389,401,439,457,461,467,487,499, %U A023213 509,521,571,577,587,599,647,661,677,691,719,769,797,829,839,877,881,907,929,941 %N A023213 Primes p such that 4p + 3 is prime. %H A023213 Vincenzo Librandi, <a href="/A023213/b023213.txt">Table of n, a(n) for n = 1..1000</a> %t A023213 Select[Prime@Range@500, PrimeQ[4 # + 3] &] (* _Vincenzo Librandi_, May 19 2014 *) %o A023213 (Magma) [ n: n in PrimesUpTo(1000) | IsPrime(4*n+3) ]; // _Vincenzo Librandi_, Nov 20 2010 %o A023213 (PARI) select(p->isprime(4*p+3),primes(100)) \\ _Charles R Greathouse IV_, Mar 21 2013 %Y A023213 Cf. A007700. %K A023213 nonn,easy %O A023213 1,1 %A A023213 _David W. Wilson_