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 A122724 #18 May 14 2025 22:56:41
%S A122724 2,3,7,19,47,83,487
%N A122724 Primes p such that (2p)! - 1 is also prime.
%C A122724 Corresponding primes of the form (2p)! - 1 are {23,719,87178291199,523022617466601111760007224100074291199999999,...}.
%C A122724 No other terms < 20663. - _Robert Price_, Mar 02 2012
%C A122724 No other terms < 104002 using A002982. - _Michael S. Branicky_, May 14 2025
%t A122724 Select[Prime[Range[100]],PrimeQ[(2#)!-1]&] (* _James C. McMahon_, Nov 09 2024 *)
%Y A122724 Cf. A002982, A103317.
%K A122724 hard,more,nonn
%O A122724 1,1
%A A122724 _Alexander Adamchuk_, Sep 23 2006