Search: id:A071628
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%I A071628
%S A071628 1,1,1,2,1,1,2,1,3,6,1,1,2,1,1,8,1,1,2,1,1,2,2,583,2,1,1,1,2,5,4,1,1,2,
%T A071628 1,3,2,1,3,2,1,1,4,2,1,4,2,1,2,1,3,16,1,3,6,1,1,2,2,1,4,2,1,2,3,1,4,1,
%U A071628 3,2,1,3,2,1,3,4,1,1,8,2,3,2,1,7,2,1,1,2,2,1,4,1,3,4,1,1,2,2,15,2,3,2
%N A071628 Smallest m such that (2n-1)*2^m is totient, i.e. is in A002202.
%F A071628 a(n)=Min[{x; Card(InvPhi[(2n-1)*(2^x)])>0}]
%e A071628 n=52:2n-1=13, [seq(nops(invphi(103*2^i)),i=1..25)]; gives: [0,0,0,0,0,
               0,0,0,0,0,0,0,0,0,0,2,3,6,8,10,12,14,16,18,20]; nonzero appears first 
               at position 16, so a(52)=16,since 6750208=103.2^16 is totient, while 
               3375104 is non-totient. n=24, 2n-1=47: the first non-empty InvPhi(47.2^i) 
               set arises at i=a[24]=583, a very large number.
%p A071628 with(numtheory); [seq(nops(invphi(odd*2^i)),i=1..N)]; Position of first 
               nonzero provides a[n] belonging to 2n-1 odd number.
%Y A071628 Similar to but different from A046067. See also A058887, A057192.
%Y A071628 Cf. A000010, A002202, A007617, A046067, A058887, A057192.
%Y A071628 Sequence in context: A076302 A104524 A128807 this_sequence A033809 A046067 
               A132066
%Y A071628 Adjacent sequences: A071625 A071626 A071627 this_sequence A071629 A071630 
               A071631
%K A071628 nonn
%O A071628 1,4
%A A071628 Labos E. (labos(AT)ana.sote.hu), May 30 2002

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