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 A172461 #10 Jul 29 2020 03:18:53 %S A172461 2,3,7,19,31,607,1279,2281,44497,1257787,13466917 %N A172461 Primes p such that 2*p-1 and 2^p-1 are both primes. %e A172461 a(1) = 2 is a term since it is a prime and 2^2 - 1 = 3 and 2*2 - 1 = 3 are primes. %e A172461 a(2) = 3 is a term since it is a prime and 2^3 - 1 = 7 and 2*3 - 1 = 5 are primes. %t A172461 Select[MersennePrimeExponent[Range[47]], PrimeQ[2# -1] &] (* _Amiram Eldar_, Jul 29 2020 *) %Y A172461 Intersection of A000043 and A005382. %Y A172461 Cf. A000668. %K A172461 nonn,more %O A172461 1,1 %A A172461 _Juri-Stepan Gerasimov_, Feb 03 2010, Feb 06 2010 %E A172461 a(9)-a(11) from _Robert G. Wilson v_, Feb 26 2010