login
Primes p with the period of the decimal fraction 1/p a prime power, A000961.
2

%I #18 Mar 30 2012 17:23:02

%S 3,11,17,37,41,53,73,79,83,101,107,137,163,173,227,239,257,271,317,

%T 347,353,359,449,467,479,563,587,641,643,719,733,751,757,773,797,839,

%U 907,1031,1187,1231,1283,1307,1319,1409,1439,1493,1523,1627,1637,1879,1907

%N Primes p with the period of the decimal fraction 1/p a prime power, A000961.

%H T. D. Noe, <a href="/A197225/b197225.txt">Table of n, a(n) for n = 1..1000</a>

%t myPerfectPowerQ[n_] := Length[FactorInteger[n]] == 1; Select[Prime[Range[500]], Mod[10,#] > 0 && myPerfectPowerQ[Length[RealDigits[1/#, 10][[1,1]]]] &]

%Y Cf. A072859 (period is prime).

%Y Cf. A072982 (period is a power of 2).

%Y Cf. A128948 (period is perfect power).

%Y Cf. A197226 (the periods of this sequence).

%Y Cf. A129727 (period is a semiprime).

%K nonn,base

%O 1,1

%A _T. D. Noe_, Oct 22 2011