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 A373320 #7 Jun 01 2024 12:05:30
%S A373320 1,2,3,4,6,10,12,18,24,30,42,54,60,78,84,90,114,120,150,168,180,210,
%T A373320 270,294,300,330,390,420,510,546,570,630,750,780,840,990,1050,1170,
%U A373320 1260,1470,1650,1680,1890,2100,2310,2730,3150,3360,3570,3990,4290,4410,4620
%N A373320 Numbers k such that phi(k)/k^2 < phi(m)/m^2 for all m < k, where phi is the Euler totient function (A000010).
%C A373320 First differs from A330006 at n = 52: a(52) = 4410 is not a term of A330006. The first term of A330006 that is not in this sequence is A330006(127) = 166530.
%C A373320 Numbers are less likely to be unitary divisors than any smaller number, i.e., numbers k such that the asymptotic density of numbers that are unitarily divided by k (A373318(k)/A373319(k)) is lower than the corresponding density of all m < k.
%C A373320 The numbers k such that phi(k)/k < phi(m)/m for all m < k are the primorial numbers (A002110).
%H A373320 Amiram Eldar, <a href="/A373320/b373320.txt">Table of n, a(n) for n = 1..670</a>
%t A373320 seq[kmax_] := Module[{rm = 2, r, s = {}}, Do[If[(r = EulerPhi[k]/k^2) < rm, rm = r; AppendTo[s, k]], {k, 1, kmax}]; s]; seq[5000]
%o A373320 (PARI) lista(kmax) = {my(rm = 2, r); for(k = 1, kmax, r = eulerphi(k)/k^2; if(r < rm, rm = r; print1(k, ", ")));}
%Y A373320 Cf. A000010, A002110, A330006, A373318, A373319.
%K A373320 nonn
%O A373320 1,2
%A A373320 _Amiram Eldar_, Jun 01 2024