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 A255682 #20 Sep 08 2022 08:46:11 %S A255682 3,7,13,15,21,73,231,301,493,895,955,4069,5057,5415,15325,19845,21603, %T A255682 24577,37877,40193,44283 %N A255682 Numbers k such that 4^k - 2^k - 3 is prime. %C A255682 a(22) > 150000. - _Hans Havermann_, Jul 18 2015 %e A255682 3 is in this sequence because 4^3 - 2^3 - 3 = 53. %t A255682 Select[Range[15000], PrimeQ[4^# - 2^# - 3] &] %o A255682 (Magma) [n: n in [1..800] | IsPrime(4^n-2^n-3)]; %o A255682 (PARI) for(n=1,500,if(ispseudoprime(4^n-2^n-3),print1(n,", "))) \\ _Derek Orr_, Mar 03 2015 %Y A255682 Cf. A098845. %K A255682 nonn,more %O A255682 1,1 %A A255682 _Vincenzo Librandi_, Mar 02 2015 %E A255682 a(15)-a(21) from _Hans Havermann_, Jul 18 2015