A054513 - OEIS

%I #17 Jul 31 2021 05:10:34

%S 5,10,3,17,3,23,14,24,8,10,19,48,7,23,16,34,9,66,28,86,35,25,45,48,25,

%T 95,33,47,85,87,105,32,142,16,41,40,139,157,94,35,90,46,133,47,12,119,

%U 5,204,88,115,103,191,209,54,148,110,110,174,94,218,1,244,27,1,278,315

%N Log_b 10 where b is smallest primitive root (A001918) mod n-th prime.

%D Tom M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, Table 10.2, pp. 216-217.

%H Amiram Eldar, <a href="/A054513/b054513.txt">Table of n, a(n) for n = 5..10000</a>

%t a[n_] := Module[{p, b, lg = 1}, b = PrimitiveRoot[p = Prime[n]]; While[ PowerMod[b, lg, p] != 10, lg++]; lg]; Array[a, 100, 5] (* _Jean-François Alcover_, Sep 03 2016 *)

%o (PARI) a(n)=znlog(10,znprimroot(prime(n))) \\ _Charles R Greathouse IV_, Oct 03 2011

%Y Cf. table in A054503.

%Y Cf. A001918, A054505, A054506, A054507, A054508, A054509, A054510, A054511, A054512.

%K nonn,easy

%O 5,1

%A _N. J. A. Sloane_, Apr 09 2000

%E More terms from _James A. Sellers_, Apr 09 2000