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%I #9 Mar 26 2020 09:36:58
%S 0,24,1,18,20,25,28,12,2,14,23,19,11,22,21,6,7,26,4,8,29,17,27,13,10,
%T 5,3,16,9,15
%N Log base 3 (n) mod 31.
%D I. M. Vinogradov, Elements of Number Theory, p. 220ff.
%t a[1]=0; a[n_]:=MultiplicativeOrder[3, 31, {n}]; Array[a, 30] (* _Vincenzo Librandi_, Mar 25 2020 *)
%K nonn,fini,full
%O 1,2
%A _N. J. A. Sloane_.