Search: id:A158804
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%I A158804
%S A158804 4,8,9,16,25,27,30,32,49,60,64,70,81,84,90,105,120,121,125,128,140,150,
%T A158804 168,169,180,231,234,240,243,252,256,260,270,280,286,289,300,315,336,
%U A158804 343,350,360,361,450,456,468,480,490,504,512,520,525,528,529,532,540
%N A158804 Composite integers n which are a multiple of the sum of their prime factors.
%H A158804 Jean-Marie de Koninck, Florian Luca, <a href="http://www.ucl.ac.uk/mathematics/
               Mathematika/Volumes/Vol52_Articles/Article_6.pdf">Integers divisible 
               by the sum of their prime factors</a>, Mathematika 52 (1&2) (2005) 
               69-77, <a href="http://www.ams.org/mathscinet-getitem?mr=2261843">
               MR2261843</a>.
%F A158804 {n in A002808: A008472(n)|n }
%e A158804 4 is in the sequence because A008472(4)=2 divides 4. 5 is not in the 
               sequence because it is prime. 6 is not in the sequence because A008472(6)=5 
               does not divide 6.
%p A158804 A008472 := proc(n) numtheory[factorset](n) ; add(d,d=%) ; end: isbeta 
               := proc(n) if isprime(n) then false; else if n mod A008472(n) = 0 
               then true; else false; fi; fi; end: for n from 2 to 1200 do if isbeta(n) 
               then printf("%d,",n); fi; od:
%Y A158804 Sequence in context: A140104 A127398 A109422 this_sequence A080366 A001694 
               A157985
%Y A158804 Adjacent sequences: A158801 A158802 A158803 this_sequence A158805 A158806 
               A158807
%K A158804 easy,nonn
%O A158804 1,1
%A A158804 R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 27 2009

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