OFFSET
0,4
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..1122 (terms 1..250 from G. C. Greubel)
MATHEMATICA
Table[2^n + 1 - EulerPhi[2^n + 1], {n, 0, 50}] (* G. C. Greubel, May 31 2018 *)
PROG
(PARI) a(n) = my(x=2^n+1); x - eulerphi(x); \\ Michel Marcus, Aug 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Mar 03 2000
EXTENSIONS
Offset changed to 0 and a(0) prepended by Amiram Eldar, Jan 11 2024
STATUS
approved