OFFSET
0,2
LINKS
Max Alekseyev, Table of n, a(n) for n = 0..1122 (terms 0..300 from Robert Israel; terms 301..1062 from Amiram Eldar)
EXAMPLE
It is a power of 2 iff n is a Fermat prime.
MAPLE
seq(numtheory:-phi(2^n+1), n=0..50); # Robert Israel, Aug 12 2015
MATHEMATICA
Table[EulerPhi[2^n + 1], {n, 35}] (* Vincenzo Librandi, Aug 12 2015 *)
PROG
(PARI) vector(40, n, eulerphi(2^n+1)) \\ Michel Marcus, Aug 12 2015
(Magma) [EulerPhi(2^n+1) : n in [1..40]]; // Vincenzo Librandi, Aug 12 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Mar 03 2000
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Aug 12 2015
STATUS
approved