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 A307390 #22 Aug 14 2024 17:57:10 %S A307390 5,11,13,17,23,29,41,43,47,53,59,61,67,71,73,83,89,101,103,107,109, %T A307390 113,127,131,137,149,151,163,167,173,179,181,191,193,197,223,227,233, %U A307390 239,241,251,257,263,269,277,281,283,293,311,313,317,347,349,353,359,373,383,389,397,401,409,419,421 %N A307390 Primes p such that 2*p-1 is not prime. %C A307390 Primes not in A005382. %H A307390 Robert Israel, <a href="/A307390/b307390.txt">Table of n, a(n) for n = 1..10000</a> %F A307390 a(n) = A109274(n) + 1. - _Bhavik Mehta_, Aug 14 2024 %e A307390 a(3) = 13 is in the sequence because 13 is prime but 2*13-1 = 25 is not. %p A307390 select(t -> isprime(t) and not isprime(2*t-1), [seq(i,i=3..1000,2)]); %Y A307390 Cf. A005382, A053176, A109274. %Y A307390 Includes A007528. %K A307390 nonn %O A307390 1,1 %A A307390 _Robert Israel_, Apr 17 2019