|
%I #22 Feb 18 2021 05:41:09
%S 20,30,40,42,52,60,66,68,70,78,80,84,90,100,102,104,110,114,116,120,
%T 126,130,132,136,138,140,148,150,154,156,160,164,168,170,171,174,180,
%U 182,186,190,198,200,204,208,210,212,220,222,228,230,232,234,238,240
%N Numbers m>0 such that the number of solutions to x^m==1 (mod m), 1<=x<=m, is not equal to gcd(m, phi(m)).
%C Conjecture: limit of a(n)/n is zero.
%C This conjecture is certainly wrong as stated, because sequences "Numbers such that..." have lim a(n)/n >= 1 and a(n) > n for all indices following the first one for which this holds, as here: a(1) > 1. - _M. F. Hasler_, Feb 24 2014
%H Robert G. Wilson v, <a href="/A072989/b072989.txt">Table of n, a(n) for n = 1..220</a>
%F Equals { m>0 | A009195(m) != A072994(m) }. - _M. F. Hasler_, Feb 23 2014
%o (PARI) isok(m) = sum(x=1, m, Mod(x, m)^m==1) != gcd(m, eulerphi(m)); \\ _Michel Marcus_, Feb 18 2021
%Y Cf. A009195, A072994.
%K easy,nonn
%O 1,1
%A _Benoit Cloitre_, Aug 21 2002
|
