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 A111089 #14 Nov 01 2019 16:22:37
%S A111089 2,2,3,2,5,3,7,2,3,5,11,3,13,7,5,2,17,3,19,5,7,11,23,3,5,13,3,7,29,5,
%T A111089 31,2,11,17,7,3,37,19,13,5,41,7,43,11,5,23,47,3,7,5,17,13,53,3,11,7,
%U A111089 19,29,59,5,61,31,7,2,13,11,67,17,23,7,71,3,73,37,5,19,11,13,79,5,3,41,83,7
%N A111089 Largest prime factor of 2n.
%C A111089 For composite indices we have a(n*m) = max(a(n), a(m)). - _Stefan Steinerberger_, Nov 13 2005
%C A111089 Same as A006530 except for initial term. - _Franklin T. Adams-Watters_, Jul 17 2008
%t A111089 Table[FactorInteger[2n][[ -1, 1]], {n, 100}] (* _Ray Chandler_, Nov 12 2005 *)
%Y A111089 Bisection of A006530.
%K A111089 nonn
%O A111089 1,1
%A A111089 _Giovanni Teofilatto_, Nov 12 2005
%E A111089 Corrected and extended by _Ray Chandler_ and _Stefan Steinerberger_, Nov 12 2005