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Sum of prime factors of phi(n).
1

%I #9 May 30 2020 10:26:16

%S 2,2,2,2,5,2,5,2,7,2,5,5,2,2,2,5,5,2,5,7,13,2,7,5,5,5,9,2,10,2,7,2,5,

%T 5,5,5,5,2,7,5,12,7,5,13,25,2,12,7,2,5,15,5,7,5,5,9,31,2,10,10,5,2,5,

%U 7,16,2,13,5,14,5,5,5,7,5,10,5,18,2,5,7,43,5,2,12,9,7,13,5,5,13,10,25,5,2,5

%N Sum of prime factors of phi(n).

%H Indranil Ghosh, <a href="/A080647/b080647.txt">Table of n, a(n) for n = 3..10000</a>

%F a(n) = A008472(A000010(n)). - _Indranil Ghosh_, Jan 18 2017

%e For n = 11, phi(11) = 10 which has prime factors 2 and 5. So, 2+5 = 7 and a(11) = 7. - _Indranil Ghosh_, Jan 18 2017

%t Table[Apply[Plus, Transpose[FactorInteger[EulerPhi[n]]][[1]]], {n, 3, 100}]

%t Table[Total[FactorInteger[EulerPhi[n]][[All,1]]],{n,3,100}] (* _Harvey P. Dale_, May 30 2020 *)

%Y Cf. A000010, A008472.

%K nonn

%O 3,1

%A _Joseph L. Pe_, Feb 28 2003