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A098937 Number of cyclic numbers, primes with primitive root 10, (A001913) in the first 10^n primes (A000040). 0
5, 38, 387, 3755, 37523, 374126, 3740610, 37393725, 373953691, 3739544360 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

FORMULA

Lim_{n->oo} a(n)/10^n = Artin's constant (A005596).

MATHEMATICA

f[n_Integer] := Block[{ds = Divisors[n - 1]}, (n - 1)/Take[ds, Position[ PowerMod[10, ds, n], 1][[1, 1]]][[ -1]]]; c = 0; k = 4; Do[ While[k <= 10^n, a = f[ Prime[k]]; If[a == 1, c++ ]; k++ ]; Print[c], {n, 7}]

CROSSREFS

Cf. A001913, A006883, A000040, A005596.

Sequence in context: A335530 A308877 A322908 * A190314 A217701 A069471

Adjacent sequences:  A098934 A098935 A098936 * A098938 A098939 A098940

KEYWORD

base,more,nonn

AUTHOR

Robert G. Wilson v, Oct 19 2004

EXTENSIONS

a(8)-a(10) from Amiram Eldar, Jul 04 2021

STATUS

approved

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Last modified December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)