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 A368696 #5 Jan 09 2024 16:56:18
%S A368696 9,21,25,33,49,57,69,85,93,121,129,133,145,161,169,177,185,201,205,
%T A368696 209,213,217,221,237,249,253,265,289,305,309,315,321,341,361,365,377,
%U A368696 381,393,413,417,437,445,453,469,485,489,493,495,497,501,505,517,529,537,545,553,565,573,597,633,649,669,681,685,689
%N A368696 Numbers whose arithmetic derivative (A003415) is a squarefree number of the form 4k+2.
%o A368696 (PARI)
%o A368696 A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o A368696 isA368696(n) = { my(d=A003415(n)); ((2==(d%4))&&issquarefree(d)); };
%Y A368696 Intersection of A327862 and A328393.
%Y A368696 Cf. A003415, A005117, A368697 (subsequence).
%K A368696 nonn
%O A368696 1,1
%A A368696 _Antti Karttunen_, Jan 09 2024