OFFSET
1,4
COMMENTS
Number of elements in GF(2^n) that do not have maximal order. a(n)=1 if n is the exponent of a Mersenne prime, the single element which is not a generator for these is the unit. - Joerg Arndt, Jul 05 2011
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1206 (terms 1..250 from G. C. Greubel)
MATHEMATICA
Table[2^n - 1 - EulerPhi[2^n - 1], {n, 1, 50}] (* G. C. Greubel, May 31 2018 *)
PROG
(PARI) a(n)={my(m=2^n-1); return(m-eulerphi(m)); }
vector(66, n, a(n)) /* Joerg Arndt, Jul 05 2011 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Mar 03 2000
STATUS
approved