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 A056211 Primes p for which the period of reciprocal = (p-1)/6. 5

%I

%S 79,547,643,751,907,997,1201,1213,1237,1249,1483,1489,1627,1723,1747,

%T 1831,1879,1987,2053,2551,2683,3049,3253,3319,3613,3919,4159,4507,

%U 4519,4801,4813,4831,4969,5119,5443,5557,5791,6079,6151,6271,6373,6427,6529

%N Primes p for which the period of reciprocal = (p-1)/6.

%C Cyclic numbers of the sixth degree (or sixth order): the reciprocals of these numbers belong to one of six different cycles. Each cycle has the (number minus 1)/6 digits.

%H T. D. Noe, <a href="/A056211/b056211.txt">Table of n, a(n) for n=1..1000</a>

%H <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a>

%t f[n_Integer] := Block[{ds = Divisors[n - 1]}, (n - 1)/Take[ ds, Position[ PowerMod[ 10, ds, n], 1] [[1, 1]]] [[ -1]]]; Select[ Prime[ Range[4, 850]], f[ # ] == 6 &]

%Y Cf. A001913, A097443, A055628, A056157, A056210-A056217, A098680

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Aug 02 2000

%E Edited by _N. J. A. Sloane_, Apr 30 2007

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Last modified May 31 12:20 EDT 2020. Contains 334748 sequences. (Running on oeis4.)