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 A066694 #19 Sep 10 2024 08:44:30
%S A066694 4,9,16,18,25,32,36,48,50,64,72,81,84,98,100,112,144,156,162,192,196,
%T A066694 200,225,252,256,288,289,300,324,336,338,372,392,400,432,448,450,468,
%U A066694 484,512,576,578,624,625,648,676,700,722,729,756,768,784,800,882,900
%N A066694 Numbers k such that phi(sigma(k)) > k.
%H A066694 Harry J. Smith, <a href="/A066694/b066694.txt">Table of n, a(n) for n = 1..1000</a>
%H A066694 Amiram Eldar, <a href="/A066694/a066694.jpg">Plot of a(n)/(n*log(n)^2) for n = 2^(4..21)</a>.
%F A066694 It seems that a(n) is asymptotic to C*n*log(n)^2 with C=1.38.... - _Benoit Cloitre_, Aug 07 2002
%t A066694 Select[Range[1, 10^3], EulerPhi[DivisorSigma[1, # ]] > # &]
%o A066694 (PARI) { n=0; for (m=1, 10^10, if (eulerphi(sigma(m)) > m, write("b066694.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Mar 18 2010
%Y A066694 Cf. A000010, A000203, A001229, A062401, A295307.
%K A066694 easy,nonn
%O A066694 1,1
%A A066694 _Joseph L. Pe_, Jan 09 2002
%E A066694 More terms from _Benoit Cloitre_, Jul 31 2002