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 A336594 #13 Nov 13 2020 10:37:27 %S A336594 4,9,12,18,20,25,28,36,44,45,49,50,52,60,63,64,68,75,76,84,90,92,98, %T A336594 99,100,116,117,121,124,126,132,140,144,147,148,150,153,156,164,169, %U A336594 171,172,175,180,188,192,196,198,204,207,212,220,225,228,234,236,242,244 %N A336594 Numbers k such that k/A008835(k) is cubefree but not squarefree (A067259), where A008835(k) is the largest 4th power dividing k. %C A336594 Numbers such that at least one of the exponents in their prime factorization is of the form 4*m + 2, and none are of the form 4*m + 3. %C A336594 The asymptotic density of this sequence is zeta(4) * (1/zeta(3) - 1/zeta(2)) = Pi^4/(90*zeta(3)) - Pi^2/15 = 0.2424190509... (Cohen, 1963). %H A336594 Amiram Eldar, <a href="/A336594/b336594.txt">Table of n, a(n) for n = 1..10000</a> %H A336594 Eckford Cohen, <a href="https://eudml.org/doc/140760">Arithmetical Notes, XIII. A Sequal to Note IV</a>, Elemente der Mathematik, Vol. 18 (1963), pp. 8-11. %e A336594 4 is a term since the largest 4th power dividing 4 is 1, and 4/1 = 4 = 2^2 is cubefree but not squarefree. %e A336594 64 is a term since the largest 4th power dividing 64 is 16, and 64/16 = 4 = 2^2 is cubefree but not squarefree. %t A336594 Select[Range[250], Max[Mod[FactorInteger[#][[;; , 2]], 4]] == 2 &] %Y A336594 Cf. A002117, A008835, A013661, A013662, A067259, A182358. %Y A336594 Complement of A336593 within A252849. %Y A336594 A030140 is a subsequence. %K A336594 nonn %O A336594 1,1 %A A336594 _Amiram Eldar_, Jul 26 2020