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%I #8 Mar 12 2021 23:13:58
%S 9,15,25,35,49,95,119,121,143,169,209,287,289,319,323,343,361,377,527,
%T 529,559,625,779,841,899,923,961,989,1007,1189,1199,1225,1343,1349,
%U 1369,1681,1763,1849,1919,2159,2197,2209,2507,2759,2809,2911,3239,3481,3599,3721,3827,3993,4031,4489,4607,5041,5183,5207,5249
%N Composite numbers k such that Euler totient phi(k) is a multiple of the arithmetic derivative of k.
%C The term 343 is the first one that does not occur in A070160, and 625 is the second.
%t Select[Range[5300], And[CompositeQ@ #, Mod[EulerPhi[#], Times @@ If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]] ]] == 0] &] (* _Michael De Vlieger_, Mar 12 2021 *)
%o (PARI)
%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o isA342418(n) = ((n>1)&&!isprime(n)&&!(eulerphi(n)%A003415(n)));
%Y Cf. A000010, A003415, A166374 (a subsequence after its initial terms).
%Y Subsequence of A342008.
%Y Cf. also A070160.
%K nonn
%O 1,1
%A _Antti Karttunen_, Mar 12 2021
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