Search: id:A112018
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%I A112018
%S A112018 114190259,6364631939,10296994891,10429820759
%N A112018 Primes p of the form 4k+3 where sigma(phi(sigma(p)))= phi(sigma(phi(p))).
%C A112018 Between the first 480000000 primes, the equation (*): sigma(phi(sigma(x)))=phi(sigma(phi(x))) 
               has 256 solutions q(i) and only four of them namely q(76),q(215),
               q(254) and q(256) are of the form 4k+3. Sequence A112017 gives composite 
               solutions of the equation (*), which are of the form 4k+3.
%t A112018 Do[If[Mod[Prime[m], 4]==3 && DivisorSigma[1, EulerPhi[Prime[m]+1 ==EulerPhi[DivisorSigma[1, 
               Prime[m]-1]], Print[Prime[m]]], {m, 480000000}]
%Y A112018 Cf. A112017.
%Y A112018 Sequence in context: A038451 A068538 A147581 this_sequence A157770 A015380 
               A038131
%Y A112018 Adjacent sequences: A112015 A112016 A112017 this_sequence A112019 A112020 
               A112021
%K A112018 more,nonn
%O A112018 1,1
%A A112018 Farideh Firoozbakht (mymontain(AT)yahoo.com), Sep 15 2005

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