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 A262969 #15 Nov 28 2023 17:53:51 %S A262969 1,2,4,5,7,8,20,22,43,55,67,77,92,97,154,160,533,748,1432,3143,6427, %T A262969 8257,8270,9623,12269,28822,32683,42638,97427,133340,188395,239044 %N A262969 Numbers k such that 4^k + 27 is prime. %C A262969 The next terms are > 239044. %C A262969 Contains exactly the halved even terms of A157007. %e A262969 For k = 22, 4^22 + 27 = 17592186044443 is prime. %t A262969 Select[Range[0, 250000], PrimeQ[4^# + 27] &] %o A262969 (Magma) [n: n in [0..700] | IsPrime(4^n+27)]; // _Vincenzo Librandi_, Oct 06 2015 %o A262969 (PARI) for(n=1, 1e3, if(isprime(4^n+3^3), print1(n", "))) \\ _Altug Alkan_, Oct 06 2015 %Y A262969 Cf. A157007, A253772 (similar sequence). %K A262969 nonn,more %O A262969 1,2 %A A262969 _Robert Price_, Oct 05 2015 %E A262969 a(32) derived from A157007 by _Elmo R. Oliveira_, Nov 28 2023