Search: id:A039650
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%I A039650
%S A039650 2,2,3,3,5,3,7,5,7,5,11,5,13,7,7,7,17,7,19,7,13,11,23,7,13,13,19,13,29,
%T A039650 7,31,17,13,17,13,13,37,19,13,17,41,13,43,13,13,23,47,17,43,13,13,13,
%U A039650 53,19,41,13,37,29,59,17,61,31,37,13,43,13,67,13,13,13,71,13,73,37,41
%N A039650 Prime reached by iterating f(x) = phi(x)+1 on n.
%C A039650 Or, a(n) = lim_k {s(k,n)} where s(k,n) is defined inductively on k by: 
               s(1,n) = n; s(k+1,n) = 1 + phi(s(k,n)). - Joseph L. Pe (joseph_l_pe(AT)hotmail.com), 
               Apr 30 2002
%e A039650 s(24,1) = 24, s(24,2) = 1 + phi(24) = 1 + 8 = 9, s(24,3) = 1 + phi(9) 
               = 1 + 6 = 7, s(24,4) = 1 + phi(7) = 1 + 6 = 7,.... Therefore a(24) 
               = lim_k {s(24,k)} = 7.
%t A039650 f[n_] := FixedPoint[1 + EulerPhi[ # ] &, n]; Table[ f[n], {n, 1, 75}]
%Y A039650 Cf. A039649-A039656.
%Y A039650 Sequence in context: A069933 A102347 A069974 this_sequence A039649 A113605 
               A070230
%Y A039650 Adjacent sequences: A039647 A039648 A039649 this_sequence A039651 A039652 
               A039653
%K A039650 nonn
%O A039650 1,1
%A A039650 David W. Wilson (davidwwilson(AT)comcast.net)

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