A128948 Primes p for which the period length of 1/p is a perfect power, A001597.

3, 17, 73, 101, 137, 163, 257, 353, 449, 577, 641, 751, 757, 883, 1297, 1409, 1801, 3137, 3529, 5477, 7057, 7351, 8929, 9397, 10753, 11831, 12101, 13457, 13553, 14401, 15361, 15377, 15973, 18523, 19841, 20809, 21401, 21601, 23549, 24001, 24337

Offset

1,1

Comments

Number of primes p < 10^n whose period length of 1/p is a perfect power: 1,3,14,24,78,173,461,1190,3235,8933,....

The primes modulo any integer do not seem to be equally distributed.

Links

Ray Chandler & Robert G. Wilson v, Table of n, a(n) for n = 1..30000

Index entries for sequences related to decimal expansion of 1/n

Example

The prime 73 has a period of 8 = 2^3 which is a member of A001597, hence is a member of this sequence.

Mathematica

lst = {3}; p = 1; While[p < 10^8, p = NextPrime@p; If[GCD @@ Last /@ FactorInteger@ MultiplicativeOrder[10, p] > 1, AppendTo[lst, p]; Print@p]]; lst (* Ray Chandler, May 11 2007 *)

Crossrefs

Cf. A001597, A072859, A072982.

Sequence in context: A270231 A265919 A317452 * A342364 A049181 A248917

Adjacent sequences: A128945 A128946 A128947 * A128949 A128950 A128951

Keyword

base,nonn

Author

Robert G. Wilson v, May 05 2007

Extensions

Correction (3 is a member of the sequence) from Ray Chandler, May 11 2007

B-file corrected by Ray Chandler, Oct 23 2011

Status

approved