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 A065393 #27 Feb 20 2025 06:30:23
%S A065393 3,5,7,11,13,17,19,29,31,37,41,53,61,73,95,97,109,127,143,157,181,209,
%T A065393 241,287,313,323,337,377,403,407,421,473,527,533,541,589,601,661,713,
%U A065393 731,757,779,899,1009,1073,1147,1159,1199,1271,1321,1333,1349,1517
%N A065393 Sigma(phi(m)) - phi(sigma(m)) is increasing at these values of m.
%C A065393 First composite number is the 15th term, 95. [Corrected by _Jacob Vecht_, Jul 28 2020]
%H A065393 Amiram Eldar, <a href="/A065393/b065393.txt">Table of n, a(n) for n = 1..2000</a> (terms 1..500 from Harry J. Smith)
%t A065393 a = 0; s = 0; Do[s = DivisorSigma[1, EulerPhi[n]] - EulerPhi[DivisorSigma[1, n]]; If[s>a, a = s; Print[n]], {n, 1, 10000}]
%t A065393 DeleteDuplicates[Table[{m,DivisorSigma[1,EulerPhi[m]]-EulerPhi[DivisorSigma[1,m]]},{m,1600}],GreaterEqual[#1[[2]],#2[[2]]]&][[;;,1]] (* _Harvey P. Dale_, Aug 02 2023 *)
%o A065393 (PARI) { n=r=0; for (m=1, 10^9, x=sigma(eulerphi(m)) - eulerphi(sigma(m)); if (x > r, r=x; write("b065393.txt", n++, " ", m); if (n==500, return)) ) } \\ _Harry J. Smith_, Oct 18 2009
%Y A065393 Cf. A000010, A000203, A065394, A065395.
%K A065393 nonn
%O A065393 1,1
%A A065393 _Labos Elemer_, Nov 05 2001