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 A217348 #20 Nov 28 2023 16:53:40 %S A217348 2,3,4,5,6,9,10,13,16,18,28,33,59,65,75,83,103,113,275,353,405,568, %T A217348 614,909,1184,1200,1564,2266,2556,4246,8014,8193,8696,9291,10993, %U A217348 12146,13809,15459,16381,24106,60220,91816,158070,182491,207016,266675,297561 %N A217348 Numbers k such that 4^k - 5 is prime. %F A217348 a(n) = A059608(n+1)/2. - _Daniel Starodubtsev_, Mar 20 2020 %e A217348 28 is a term because 4^28 - 5 = 72057594037927931 is prime. %t A217348 Select[Range[10000], PrimeQ[4^# - 5] &] %o A217348 (PARI) /* Up to 620 the code produces in few seconds the first terms: */ %o A217348 allocatemem(10000000); for(n=2, 620, if(isprime(4^n-5), print1(n", "))); %Y A217348 Cf. A059266, A059608, A059614. %K A217348 nonn,more %O A217348 1,1 %A A217348 _Vincenzo Librandi_, Oct 01 2012 %E A217348 a(31)-a(34) from _Bruno Berselli_, Oct 02 2012 %E A217348 a(35)-a(45) from _Daniel Starodubtsev_, Mar 20 2020 %E A217348 a(46)-a(47) derived from A059608 by _Elmo R. Oliveira_, Nov 28 2023