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 A050523 #26 Apr 29 2025 22:43:00
%S A050523 13,223,3583,917503,14680063,3758096383,246290604621823,
%T A050523 1340933598257652751063553648756520535666396731910651903
%N A050523 Primes of the form 7*2^k - 1.
%H A050523 <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a>.
%F A050523 a(n) = A086224(A001771(n)). - _Elmo R. Oliveira_, Apr 22 2025
%t A050523 Select[Table[7*2^n-1, {n,0,200}], PrimeQ] (* _Jean-François Alcover_, Mar 20 2011 *)
%Y A050523 See A001771 for more terms.
%Y A050523 Cf. A086224, A158795 [_Vincenzo Librandi_, Mar 28 2009]
%K A050523 nonn,nice
%O A050523 1,1
%A A050523 _N. J. A. Sloane_, Dec 29 1999
%E A050523 13 inserted by _R. J. Mathar_, Apr 01 2009