cp's OEIS Frontend

A370266 Numbers k that are not prime powers, such that k/rad(k) >= rad(k), where rad(k) = A007947(k).

%I A370266 #17 Feb 25 2024 12:43:08
%S A370266 36,48,54,72,96,100,108,144,160,162,192,196,200,216,224,225,250,288,
%T A370266 320,324,375,384,392,400,405,432,441,448,484,486,500,567,576,640,648,
%U A370266 675,676,686,704,768,784,800,832,864,896,900,960,968,972,1000,1029,1080,1089
%N A370266 Numbers k that are not prime powers, such that k/rad(k) >= rad(k), where rad(k) = A007947(k).
%C A370266 Numbers k = m * s, where s is composite and squarefree, rad(m) | s, and m >= s.
%C A370266 A177492 is a proper subset.
%H A370266 Michael De Vlieger, <a href="/A370266/b370266.txt">Table of n, a(n) for n = 1..10000</a>
%F A370266 Set difference of A341645 and A246547.
%F A370266 Intersection of A341645 and A126706.
%F A370266 Union of A286708 and A366250.
%e A370266 For s = 6, this sequence contains {36, 48, 54, 72, 96, ...}, i.e., A033845(n) for n >= A010846(6).
%e A370266 For s = 10, this sequence contains {100, 160, 200, 250, 320, ...}, i.e., A033846(n) for n >= A010846(10).
%e A370266 For s = 14, this sequence contains {196, 224, 392, 448, 686, ...}, i.e., A033847(n) for n >= A010846(14).
%e A370266 For s = 15, this sequence contains {225, 375, 405, 675, 1125, ...}, i.e., A033849(n) for n >= A010846(15), etc.
%t A370266 Select[Select[Range[2, 1100], Not@*PrimePowerQ], #1/#2 >= #2 & @@ {#, Times @@ FactorInteger[#][[All, 1]]} &]
%Y A370266 Cf. A007947, A010846, A024619, A120944, A126706, A177492, A246547, A286708, A341645, A366250.
%K A370266 nonn,easy
%O A370266 1,1
%A A370266 _Michael De Vlieger_, Feb 18 2024