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 A137288 #21 May 22 2025 09:22:05 %S A137288 1,2,4,8,11,12,22,25,34,37,46,47,50,58,63,67,68,73,75,85,95,101,106, %T A137288 110,111,114,121,125,129,141,145,151,159,163,168,169,180,193,203,207, %U A137288 211,222,226,232,242,254,258,260,274,285 %N A137288 Numbers k such that 2*prime(k)-1 is prime. %H A137288 Carl R. White, <a href="/A137288/b137288.txt">Table of n, a(n) for n = 1..10000</a> %e A137288 k=11: 2*prime(11) - 1 = 2*31 - 1 = 61 is prime, so k=11 belongs to the sequence. %t A137288 Select[Range[285],PrimeQ[2Prime[#]-1]&] (* _James C. McMahon_, May 22 2025 *) %Y A137288 Cf. A000040, A005382 (corresponding primes). %K A137288 easy,nonn %O A137288 1,2 %A A137288 _Ctibor O. Zizka_, Apr 05 2008 %E A137288 More terms from _Paolo P. Lava_, Apr 15 2008