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Sum of factors of numbers having exactly three prime factors.
1

%I #6 Nov 21 2013 12:48:37

%S 6,7,8,9,9,11,10,12,15,11,12,17,13,16,21,14,13,23,18,27,16,17,22,15,

%T 18,24,33,19,35,15,20,28,17,41,23,20,45,19,24,25,47,34,17,22,36,51,26,

%U 21,29,57,42,30,21,63,26,24,65,19,46,25,48,35,28,71,23,21,37,52,75,27,26

%N Sum of factors of numbers having exactly three prime factors.

%C a(n) = A001414(A014612(n)).

%C Prime factors are counted with multiplicity, e.g., 20 has three prime factors: 2 x 2 x 5. [From Harvey P. Dale, Oct 04 2011]

%H Harvey P. Dale, <a href="/A102304/b102304.txt">Table of n, a(n) for n = 0..1000</a>

%e A014612(25) = 114 = 2*3*19 -> 2+3+19 = 24 = a(25).

%t Total[Times@@@FactorInteger[#]]&/@Select[Range[300],PrimeOmega[#]==3&] (* _Harvey P. Dale_, Oct 04 2011 *)

%K nonn

%O 0,1

%A _Reinhard Zumkeller_, Feb 20 2005