login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056212 Primes p for which the period of reciprocal = (p-1)/7. 2

%I

%S 211,617,1499,2087,2857,6007,6469,7127,7211,7589,9661,10193,13259,

%T 13553,14771,18047,18257,19937,20903,21379,23549,26153,27259,27539,

%U 32299,33181,33461,34847,35491,35897,41651,42407,42491,43051,43793

%N Primes p for which the period of reciprocal = (p-1)/7.

%C Cyclic numbers of the seventh degree (or seventh order): the reciprocals of these numbers belong to one of seven different cycles. Each cycle has the (number minus 1)/7 digits.

%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, 4700]], f[ # ] == 7 &]

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Aug 02 2000

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 12 05:35 EDT 2020. Contains 335658 sequences. (Running on oeis4.)