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A056212 Primes p for which the period of reciprocal = (p-1)/7. 2
211, 617, 1499, 2087, 2857, 6007, 6469, 7127, 7211, 7589, 9661, 10193, 13259, 13553, 14771, 18047, 18257, 19937, 20903, 21379, 23549, 26153, 27259, 27539, 32299, 33181, 33461, 34847, 35491, 35897, 41651, 42407, 42491, 43051, 43793 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..35.

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

MATHEMATICA

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 &]

CROSSREFS

Sequence in context: A300334 A032659 A098674 * A299110 A236722 A236878

Adjacent sequences:  A056209 A056210 A056211 * A056213 A056214 A056215

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Aug 02 2000

EXTENSIONS

Edited by N. J. A. Sloane, Apr 30 2007

STATUS

approved

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Last modified August 20 23:06 EDT 2018. Contains 313929 sequences. (Running on oeis4.)