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%I #23 Nov 18 2020 06:52:05
%S 2,2,4,4,16,4,64,16,64,16,1024,16,4096,64,256,256,65536,64,262144,256,
%T 4096,1024,4194304,256,1048576,4096,262144,4096,268435456,256,
%U 1073741824,65536,1048576,65536,16777216,4096,68719476736,262144,16777216,65536
%N a(n) = 2^phi(n).
%H Harry J. Smith, <a href="/A066781/b066781.txt">Table of n, a(n) for n = 1..300</a>
%F From _Amiram Eldar_, Nov 18 2020: (Start)
%F a(n) = 2^A000010(n).
%F Sum_{n>=1} 1/a(n) = A334071. (End)
%t Table[2^EulerPhi[n], {n, 40}] (* _Arkadiusz Wesolowski_, Jan 16 2013 *)
%o (PARI) a(n) = 2^eulerphi(n); \\ _Harry J. Smith_, Mar 25 2010
%Y Cf. A000010, A334071.
%K nonn
%O 1,1
%A _Benoit Cloitre_, Jan 18 2002
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