%N Numbers that are cubefree, but not squarefree and whose arithmetic derivative is not squarefree.
%C Numbers n for which A051903(n) = 2 and A051903(A003415(n)) > 1.
%H Antti Karttunen, <a href="/A328304/b328304.txt">Table of n, a(n) for n = 1..10000</a>
%e 4 = 2^2 is cubefree but not squarefree, and its arithmetic derivative A003415(4) = 4 is not squarefree, thus 4 is included in this sequence.
%e 225 = 3^2 * 5^2 is cubefree but not squarefree, and its arithmetic derivative A003415(225) = 240 = 2^4 * 3 * 5 is not squarefree, thus 225 is included in this sequence.
%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o A051903(n) = if((1==n),0,vecmax(factor(n)[, 2]));
%o isA067259(n) = (2==A051903(n));
%o isA328303(n) = !issquarefree(A003415(n));
%o isA328304(n) = (isA067259(n)&&isA328303(n));
%Y Cf. A003415, A008966, A051903.
%Y Intersection of A067259 and A328303. Intersection of A067259 and A328321.
%Y Cf. A328305 (a subsequence).
%A _Antti Karttunen_, Oct 13 2019