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 A033557 #6 Jul 08 2025 19:53:44
%S A033557 4,5,7,7,9,9,11,13,15,13,15,15,17,19,21,19,21,21,23,25,27,25,27,29,31,
%T A033557 33,35,31,33,33,35,37,39,41,43,39,41,43,45,43,45,45,47,49,51,49,51,53,
%U A033557 55,57,59,55,57,59,61,63
%N A033557 2n - {largest prime < n}.
%p A033557 f := n->2*n-prevprime(n); [ seq(f(i),i=3..60) ];
%Y A033557 A049711(n) + n.
%K A033557 nonn
%O A033557 3,1
%A A033557 _N. J. A. Sloane_