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A056215 Primes p for which the period of reciprocal = (p-1)/10. 3
281, 521, 1031, 1951, 2281, 2311, 2591, 3671, 5471, 5711, 6791, 7481, 8111, 8681, 8761, 9281, 9551, 10601, 11321, 12401, 13151, 13591, 14831, 14951, 15671, 16111, 16361, 18671, 21191, 21521, 21881, 24281, 24551, 25391, 25801, 25841, 26161 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Cyclic numbers of the tenth degree (or tenth order): the reciprocals of these numbers belong to one of ten different cycles. Each cycle has the (number minus 1)/10 digits.

LINKS

Table of n, a(n) for n=1..37.

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, 3000]], f[ # ] == 10 &]

CROSSREFS

Sequence in context: A161190 A178033 A098677 * A142397 A142546 A163184

Adjacent sequences:  A056212 A056213 A056214 * A056216 A056217 A056218

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Sep 15 2004

EXTENSIONS

Entry revised by N. J. A. Sloane, Apr 30 2007

STATUS

approved

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Last modified January 17 18:48 EST 2019. Contains 319251 sequences. (Running on oeis4.)