cp's OEIS Frontend

A370409 Numbers k = m * s, where s is composite and squarefree, rad(m) divides s, and 1 < m <= s, where rad() = A007947().

%I A370409 #6 Mar 02 2024 13:35:17
%S A370409 12,18,20,24,28,36,40,44,45,50,52,56,60,63,68,75,76,80,84,88,90,92,98,
%T A370409 99,100,104,112,116,117,120,124,126,132,135,136,140,147,148,150,152,
%U A370409 153,156,164,168,171,172,175,176,180,184,188,189,196,198,204,207,208
%N A370409 Numbers k = m * s, where s is composite and squarefree, rad(m) divides s, and 1 < m <= s, where rad() = A007947().
%C A370409 A177492 is a proper subset.
%C A370409 Proper subset of A126706.
%H A370409 Michael De Vlieger, <a href="/A370409/b370409.txt">Table of n, a(n) for n = 1..10000</a>
%e A370409 Let T(j,k) = row j of A162306 and let s = A120944(n), n > 1.
%e A370409 This sequence contains finite sequences R(s) = s * T(s, 2..A010846(s)). The cardinality of R(s) is A010846(s)-1.
%e A370409 For s = 6, this sequence contains {12, 18, 24, 36},
%e A370409   i.e., A033845(2..A010846(6)).
%e A370409 For s = 10, this sequence contains {20, 40, 50, 80, 100},
%e A370409   i.e., A033846(2..A010846(10)).
%e A370409 For s = 14, this sequence contains {28, 56, 98, 112, 196},
%e A370409   i.e., A033847(2..A010846(14)).
%e A370409 For s = 15, this sequence contains {45, 75, 135, 225},
%e A370409   i.e., A033849(2..A010846(15)), etc.
%Y A370409 Cf. A005117, A007947, A120944, A126706, A162306, A177492, A370266.
%K A370409 nonn
%O A370409 1,1
%A A370409 _Michael De Vlieger_, Feb 22 2024