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 A369209 #10 Jan 16 2024 06:56:46
%S A369209 4,9,12,18,20,25,28,32,36,44,45,49,50,52,60,63,68,72,75,76,84,90,92,
%T A369209 96,98,99,100,108,116,117,121,124,126,132,140,147,148,150,153,156,160,
%U A369209 164,169,171,172,175,180,188,196,198,200,204,207,212,220,224,225,228
%N A369209 Numbers whose number of divisors has the largest prime factor 3.
%C A369209 Subsequence of A059269 and first differs from it at n = 36: A059269(136) = 44 has 15 = 3 * 5 divisors and thus is not a term of this sequence.
%C A369209 Numbers k such that A000005(k) is in A065119.
%C A369209 Numbers k such that A071188(k) = 3.
%C A369209 Equals the complement of A354181, without the terms of A036537 (i.e., complement(A354181) \ A036537).
%C A369209 The asymptotic density of this sequence is Product_{p prime} (1-1/p) * (Sum_{k>=1} 1/p^(A003586(k)-1)) - A327839 = 0.26087647470200496716... .
%H A369209 Amiram Eldar, <a href="/A369209/b369209.txt">Table of n, a(n) for n = 1..10000</a>
%t A369209 gpf[n_] := FactorInteger[n][[-1, 1]]; Select[Range[300], gpf[DivisorSigma[0, #]] == 3 &]
%o A369209 (PARI) gpf(n) = if(n == 1, 1, vecmax(factor(n)[, 1]));
%o A369209 is(n) = gpf(numdiv(n)) == 3;
%Y A369209 Cf. A000005, A003586, A006530, A036537, A065119, A336595, A071188, A211337, A211338, A327839, A354181.
%Y A369209 Subsequence of A013929 and A059269.
%Y A369209 Subsequences: A001248, A030627, A050997, A054753, A062503, A067259, A079395, A085986, A085987, A086975, A095990, A096156, A138032, A162143, A179643, A179645.
%K A369209 nonn,easy
%O A369209 1,1
%A A369209 _Amiram Eldar_, Jan 16 2024