

A100491


Periodicity of the reciprocal of the Mersenne numbers (A001348).


0



1, 6, 15, 42, 44, 1365, 3855, 74898, 44620, 39672, 195225786
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OFFSET

1,2


COMMENTS

"The answer to the second question, as to whether there is a point beyond which all primes yield periods shorter than p1, is unknown. It is widely believed that there should be infinitely many primes for which the period is exactly p1, but at present we cannot be certain." [Ball]


REFERENCES

Keith Ball, Strange Curves, Counting Rabbits and other Mathematical Explorations, Princeton University Press, Princeton and Oxford, 2003, Page 57.


LINKS

Table of n, a(n) for n=1..11.


MATHEMATICA

f[n_] := Block[{ds = Divisors[n  1]}, p = Position[ PowerMod[10, ds, n], 1]; If[p == {}, Length[ RealDigits[1/n][[1, 1]]], Take[ds, p[[1, 1]]][[ 1]]]]; Table[ f[2^Prime[n]  1], {n, 11}]


CROSSREFS

Cf. A001348.
Sequence in context: A273829 A114696 A106368 * A220030 A230165 A271687
Adjacent sequences: A100488 A100489 A100490 * A100492 A100493 A100494


KEYWORD

base,nonn


AUTHOR

Robert G. Wilson v, Nov 22 2004


STATUS

approved



