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 A262971 #16 Nov 28 2023 18:35:03 %S A262971 2,6,18,270,422,596,6068,42140,64178,158732,1509278 %N A262971 Numbers k such that 4^k + 31 is prime. %C A262971 The next terms are > 1.5*10^6. %C A262971 Contains exactly the halved even terms of A247952. %F A262971 a(n) = A247952(n)/2. - _Elmo R. Oliveira_, Nov 28 2023 %e A262971 For k = 18, 4^18 + 31 = 68719476767 is prime. %t A262971 Select[Range[0, 250000], PrimeQ[4^# + 31] &] %o A262971 (Magma) [n: n in [0..700] | IsPrime(4^n+31)]; // _Vincenzo Librandi_, Oct 06 2015 %o A262971 (PARI) for(n=1, 1e3, if(isprime(4^n+31), print1(n", "))) \\ _Altug Alkan_, Oct 06 2015 %Y A262971 Cf. A247952, A253772 (similar sequence). %K A262971 nonn,more %O A262971 1,1 %A A262971 _Robert Price_, Oct 05 2015 %E A262971 a(11) derived from A247952 by _Elmo R. Oliveira_, Nov 28 2023