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 A053574 Exponent of 2 in phi(n) where phi(n) = A000010(n). 3

%I

%S 0,0,1,1,2,1,1,2,1,2,1,2,2,1,3,3,4,1,1,3,2,1,1,3,2,2,1,2,2,3,1,4,2,4,

%T 3,2,2,1,3,4,3,2,1,2,3,1,1,4,1,2,5,3,2,1,3,3,2,2,1,4,2,1,2,5,4,2,1,5,

%U 2,3,1,3,3,2,3,2,2,3,1,5,1,3,1,3,6,1,3,3,3,3,3,2,2,1,3,5,5,1,2,3,2,5,1,4,4,2,1,2,2,3,3,4,4,2,3,3,3,1,5,5

%N Exponent of 2 in phi(n) where phi(n) = A000010(n).

%H Antti Karttunen, <a href="/A053574/b053574.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007814(A000010(n)).

%F A000010(n) = A053575(n) * 2^a(n). - _Antti Karttunen_, May 26 2017

%e For n = 513 = 27*19, phi(513) = 4*81 so exponent of 2 is 2, thus a(513) = 2.

%t IntegerExponent[Array[EulerPhi, 120], 2] (* _Michael De Vlieger_, Aug 16 2017 *)

%o (PARI) vector(66,n,valuation(eulerphi(n),2)) \\ _Joerg Arndt_, Apr 22 2011

%Y Cf. A000010, A053575, A286572.

%K nonn

%O 1,5

%A _Labos Elemer_, Jan 18 2000

%E Data section extended to 120 terms by _Antti Karttunen_, May 26 2017

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Last modified April 20 22:22 EDT 2019. Contains 322310 sequences. (Running on oeis4.)