A066781 a(n) = 2^phi(n).

2, 2, 4, 4, 16, 4, 64, 16, 64, 16, 1024, 16, 4096, 64, 256, 256, 65536, 64, 262144, 256, 4096, 1024, 4194304, 256, 1048576, 4096, 262144, 4096, 268435456, 256, 1073741824, 65536, 1048576, 65536, 16777216, 4096, 68719476736, 262144, 16777216, 65536

Offset: 1

Author

Benoit Cloitre, Jan 18 2002

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..300

Crossrefs

Cf. A000010, A334071.

Programs

Mathematica

Table[2^EulerPhi[n], {n, 40}] (* Arkadiusz Wesolowski, Jan 16 2013 *)

PARI

a(n) = 2^eulerphi(n); \\ Harry J. Smith, Mar 25 2010

Formula

From Amiram Eldar, Nov 18 2020: (Start)

a(n) = 2^A000010(n).

Sum_{n>=1} 1/a(n) = A334071. (End)