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 A066765 #22 Jan 21 2025 13:32:35
%S A066765 30030,39270,43890,46410,51870,53130,60060,78540,87780,90090,92820,
%T A066765 103740,106260,117810,120120,131670,139230,150150,155610,157080,
%U A066765 159390,175560,180180,185640,196350,207480,210210,212520,219450,232050,235620
%N A066765 Numbers k such that phi(k) < k/5.
%H A066765 Amiram Eldar, <a href="/A066765/b066765.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harry J. Smith)
%F A066765 a(n) ~ kn for some constant k. k seems to be near 6500. - _Charles R Greathouse IV_, Jan 16 2025
%t A066765 Select[Range[250000], EulerPhi[#] < #/5 &] (* _Amiram Eldar_, Apr 07 2024 *)
%o A066765 (PARI) for(n=1,10^8, if(eulerphi(n)<n/5,print1(n,",")))
%o A066765 (PARI) { n=0; for (m=1, 10^10, if (eulerphi(m) < m/5, write("b066765.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Mar 24 2010
%o A066765 (PARI) list(lim)=my(v=List()); forfactored(n=30030,lim\1, if(5*eulerphi(n)<n[1], listput(v,n[1]))); Vec(v) \\ _Charles R Greathouse IV_, Jan 16 2025
%Y A066765 Cf. A000010 (phi), A091454.
%K A066765 easy,nonn
%O A066765 1,1
%A A066765 _Jason Earls_, Jan 17 2002