%I
%S 7,17,19,23,29,47,49,59,61,97,109,113,131,149,167,179,181,193,223,229,
%T 233,257,263,269,289,313,337,343,361,367,379,383,389,419,433,461,487,
%U 491,499,503,509,529,541,571,577,593,619,647,659,701,709,727,743,811
%N Numbers with primitive root 10.
%C Numbers n such that the decimal expansion of 1/n has period phi(n). For example, 1/49 has period 42.
%H Vincenzo Librandi, <a href="/A167797/b167797.txt">Table of n, a(n) for n = 1..1000</a>
%t pr=10; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &]
%Y Cf. A001913 (primes with primitive root 10)
%K nonn
%O 1,1
%A _T. D. Noe_, Nov 12 2009
