Search: id:A055234
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%I A055234
%S A055234 1,3,2,14,56,6,12,42,30,168,2580,210,630,420,840,20790,416640,9240,
%T A055234 291060,83160,120120,5165160,1719277560,43825320,26860680,277560360,
%U A055234 1304863560,569729160,587133466920,16522145640,33044291280
%N A055234 Smallest x such that sigma(x) = n*phi(x), or -1 if no such x exists.
%C A055234 Conjecture: For each n, a(n) > 0. - Farideh Firoozbakht (mymontain(AT)yahoo.com), 
               Sep 12 2004
%F A055234 a(n) = Min{x : A000203(x)/A000010(x) = n} = Min{x : A023897(x) = n}
%e A055234 sigma(14) = 24 = 4*phi(14), so a(4) = 14.
%e A055234 n = 21: a(21) = 120120 = 2.2.2.3.5.7.11.13, sigma(120120) = 483840 = 
               n*phi(120120), phi(120120) = 23040.
%t A055234 a[n_]:=(For[m=1,DivisorSigma[1,m]!=n EulerPhi[m],m++ ];m);Do[Print[a[n]], 
               {n,31}] [From Farideh Firoozbakht (mymontain(AT)yahoo.com), Oct 31 
               2008]
%Y A055234 Cf. A000203, A000010, A020492, A023897, A088830.
%Y A055234 Sequence in context: A064536 A163355 A145747 this_sequence A086485 A068310 
               A033314
%Y A055234 Adjacent sequences: A055231 A055232 A055233 this_sequence A055235 A055236 
               A055237
%K A055234 nonn
%O A055234 1,2
%A A055234 Jud McCranie (j.mccranie(AT)comcast.net), Jun 21 2000
%E A055234 More terms from Farideh Firoozbakht (mymontain(AT)yahoo.com), Sep 12 
               2004

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