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 A185307 #24 Jun 05 2023 19:35:35
%S A185307 1,15,21,33,35,39,45,51,55,57,63,65,69,70,75,77,85,87,91,93,95,99,110,
%T A185307 111,115,117,119,123,129,130,133,135,140,141,143,145,147,153,154,155,
%U A185307 159,161,170,171,175,177,182,183,185,187,189,190,201,203,205,207,209
%N A185307 Numbers not divisible by the number of their distinct prime factors.
%C A185307 The complement of A075592 (omega(n) divides n).
%C A185307 Though initially sparse, the sequence increases in density. There are more numbers divisible by omega(n) than not from [3,9265], but there are always more indivisible numbers thereafter.
%C A185307 There are 308 more numbers divisible than indivisible in the range from 1 to 2754, 2778, and 2880. This three values are the global maxima.
%C A185307 The asymptotic density of this sequence is 1 (Cooper and Kennedy, 1989). - _Amiram Eldar_, Jul 10 2020
%H A185307 Christian N. K. Anderson, <a href="/A185307/b185307.txt">Table of n, a(n) for n = 1..10000</a>
%H A185307 Curtis N. Cooper and Robert E. Kennedy, <a href="http://www.jstor.org/stable/2323194">Chebyshev's inequality and natural density</a>, Amer. Math. Monthly, Vol. 96, No. 2 (1989), pp. 118-124.
%e A185307 The distinct prime factors of 45 are 3 and 5, but 45 is not divisible by 2.
%t A185307 Join[{1},Select[Range[2,300],Mod[#,PrimeNu[#]]!=0&]] (* _Harvey P. Dale_, Jun 05 2023 *)
%o A185307 (R) library(numbers); isint<-function(x) x==as.integer(x); which(!vapply(1:500,function(n) isint(n/omega(n)),T))
%o A185307 (PARI) isok(n) = iferr(n % omega(n), E, 1); \\ _Michel Marcus_, Jul 10 2020
%Y A185307 Cf. A075592 (complement), A001221, A001222, A074946, A134334.
%K A185307 nonn
%O A185307 1,2
%A A185307 _Christian N. K. Anderson_ and _Kevin L. Schwartz_, Apr 23 2013