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 A119386 #24 Jan 08 2025 02:07:28 %S A119386 0,1,2,3,8,9,27,29,50,60,252,651,1617,7374,8051,11391,17328,32382, %T A119386 35433,97470 %N A119386 Numbers k such that 2^(2*k) - (2*k-1) is prime. %C A119386 a(18) > 30000, if it exists. - _Amiram Eldar_, Dec 01 2021 %t A119386 Select[Range[0,2000],PrimeQ[2^(2#)-(2#-1)]&] (* _Harvey P. Dale_, May 20 2012 *) %o A119386 (PARI) for(x=0,1000,if(isprime(2^(2*x)-(2*x-1)),print1(x,","))) %Y A119386 Cf. A100102. %K A119386 nonn,more %O A119386 1,3 %A A119386 _Jorge Coveiro_, Jul 25 2006 %E A119386 a(14)-a(17) from _Amiram Eldar_, Dec 01 2021 %E A119386 a(18)-a(19) from _Michael S. Branicky_, May 15 2023 %E A119386 a(20) from _Michael S. Branicky_, Jan 07 2025