Search: id:A039777
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%I A039777
%S A039777 2,5,21,45,285,765,27645,196605,41067645,72787965
%N A039777 phi(a(n)) is equal to the sum of (the product of prime factors and the 
               products of exponents) of (a(n)-1).
%C A039777 Next term if it exists is >= 10^8.
%e A039777 phi(21)=12, 20=2^2*5^1, (2*2)+(5*1)=20.
%Y A039777 Cf. A000010, A039696.
%Y A039777 Sequence in context: A006893 A003163 A088498 this_sequence A000941 A000131 
               A152801
%Y A039777 Adjacent sequences: A039774 A039775 A039776 this_sequence A039778 A039779 
               A039780
%K A039777 nonn,hard
%O A039777 1,1
%A A039777 Olivier Gerard (olivier.gerard(AT)gmail.com)
%E A039777 More terms from Jud McCranie (j.mccranie(AT)comcast.net)

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