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 A071939 #13 Aug 07 2023 05:14:02
%S A071939 0,2,2,5,3,8,6,9,9,12,8,18,16,16,16,19,15,23,21,24,24,24,20,38,38,38,
%T A071939 38,38,32,44,42,42,42,42,42,61,55,55,55,55,51,56,54,54,54,54,50,78,78,
%U A071939 78,78,78,72,72,72,72,72,72,66,110,108,108,108,108,108,108,102,102,102
%N A071939 a(n) = Max { sigma(k) : k = 1, 2, 3, ..., n } - Max { Phi(k) : k = 1, 2, 3, ..., n }.
%C A071939 Is there a simple expression for lim_{n->oo} a(n)/n?
%F A071939 a(n) = A070324(n) - A070320(n).
%t A071939 nn=70;With[{sig=DivisorSigma[1,Range[nn]],phi=EulerPhi[Range[ nn]]}, Table[ Max[Take[sig,n]]-Max[Take[phi,n]],{n,nn}]] (* _Harvey P. Dale_, May 06 2012 *)
%o A071939 (PARI) for(n=1,100,v=vector(n,x, sigma(x)); w=vector(n,y,eulerphi(y)); print1(vecmax(v)-vecmax(w),","))
%K A071939 easy,nonn
%O A071939 1,2
%A A071939 _Benoit Cloitre_, Jun 15 2002