OFFSET
1,5
LINKS
T. D. Noe,Table of n, a(n) for n = 1..10000
S. R. Finch,Idempotents and Nilpotents Modulo n,arXiv:math/0605019 [math.NT], 2006-2017.
Eric Weisstein's World of Mathematics,Primitive Root.
MAPLE
A046144:= proc(n)
local a, eulphi, m;
if n = 1 then
return 1;
end if;
eulphi:= numtheory[phi](n);
a:= 0;
for m from 0 to n-1 do
if numtheory[order](m, n) = eulphi then
a:= a + 1;
end if;
end do:
a;
end proc: #R. J. Mathar,Jan 12 2016
MATHEMATICA
Prepend[ Table[ If[ IntegerQ[ PrimitiveRoot[n]], EulerPhi[ EulerPhi[n]], 0], {n, 2, 91}], 1] (*Jean-François Alcover,Sep 13 2011 *)
PROG
(PARI) for(i=1, 100, p=0; for(q=1, i, if(gcd(q, i)==1 && znorder(Mod(q, i)) == eulerphi(i), p++)); print1(p, "," )) /*V. Raman,Nov 22 2012 */
(PARI) a(n) = my(s=znstar(n)); if(#(s.cyc)>1, 0, eulerphi(s.no)) \\Jeppe Stig Nielsen,Oct 18 2019
(Perl) use ntheory ":all"; my @A = map {!defined znprimroot($_)? 0: euler_phi(euler_phi($_)); } 0..10000; say "$_ $A[$_]" for 1..$#A; #Dana Jacobsen,Apr 28 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved