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Search: id:A007138
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| A007138 |
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Smallest primitive factor of 10^n -1. Also smallest prime p such that 1/p has repeating decimal expansion of period n.
(Formerly M2888)
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+0
14
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| 3, 11, 37, 101, 41, 7, 239, 73, 333667, 9091, 21649, 9901, 53, 909091, 31, 17, 2071723, 19, 1111111111111111111, 3541, 43, 23, 11111111111111111111111, 99990001, 21401, 859, 757, 29, 3191, 211, 2791, 353, 67, 103, 71, 999999000001
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.
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LINKS
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J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
S. S. Wagstaff, Jr., The Cunningham Project
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Index entries for sequences related to decimal expansion of 1/n
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EXAMPLE
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a(3) = 37 since 1/37 = 0.027027... has period 3.
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CROSSREFS
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Cf. A046107.
Sequence in context: A069358 A108544 A095088 this_sequence A046107 A061075 A005422
Adjacent sequences: A007135 A007136 A007137 this_sequence A007139 A007140 A007141
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KEYWORD
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nonn
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AUTHOR
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njas, Mira Bernstein, Robert G. Wilson v (rgwv(AT)rgwv.com), Jud McCranie
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