Search: id:A069819
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%I A069819
%S A069819 30,60,90,120,150,180,240,270,300,360,450,480,540,600,720,750,810,858,
%T A069819 900,960,1080,1200,1350,1440,1500,1620,1716,1722,1800,1920,2160,2250,
%U A069819 2400,2430,2574,2700,2880,3000,3240,3432,3444,3600,3750,3840,4050,4320
%N A069819 Numbers n such that 1/(sum(p|n,1/p)-1), where p are the prime divisors 
               of n, is an integer.
%C A069819 Sequence is generated by A007850(n). For example: 30,858,1722 (30=2*3*5, 
               858=2*3*11*13, 1722=2*3*11*13) generate numbers of the form 2^a*3^b*5^c, 
               2^a*3^b*7^c*41^d, 2^a*3^b*11^c*13^d, (a,b,c,d => 1), which are in 
               the sequence.
%e A069819 E.g. if n=30=2*3*5 1/(sum(p|n,1/p)-1)=1/(1/2+1/3+1/5-1)=30 hence 30 is 
               in the sequence.
%Y A069819 Sequence in context: A074915 A056954 A050519 this_sequence A143207 A108454 
               A064783
%Y A069819 Adjacent sequences: A069816 A069817 A069818 this_sequence A069820 A069821 
               A069822
%K A069819 easy,nonn
%O A069819 1,1
%A A069819 Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 28 2002

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