OFFSET
1,5
MATHEMATICA
Table[SelectFirst[Range[EulerPhi[n]], PowerMod[9, #, n]==1&], {n, 90}]/. Missing[ "NotFound"] -> 0 (* Harvey P. Dale, Jan 22 2023 *)
PROG
(PARI) a(n) = {for (i = 1, eulerphi(n), if ((9^i % n) == 1, return(i)); ); return (0); } \\Michel Marcus, Jul 31 2013
(Magma) [0] cat [Modorder(9, n): n in [2..100]]; // Vincenzo Librandi, Apr 01 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane and Amarnath Murthy, May 08 2002
STATUS
approved