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A211245
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Order of 9 mod n-th prime: least k such that prime(n) divides 9^k-1.
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13
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1, 0, 2, 3, 5, 3, 8, 9, 11, 14, 15, 9, 4, 21, 23, 26, 29, 5, 11, 35, 6, 39, 41, 44, 24, 50, 17, 53, 27, 56, 63, 65, 68, 69, 74, 25, 39, 81, 83, 86, 89, 45, 95, 8, 98, 99, 105, 111, 113, 57, 116, 119, 60, 125, 128, 131, 134, 15, 69, 140, 141, 146, 17, 155, 39
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) <= (prime(n) - 1)/2. Those prime(n) for which a(n) = (prime(n) - 1)/2 are listed in A364867. (End)
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MATHEMATICA
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nn = 9; Table[If[Mod[nn, p] == 0, 0, MultiplicativeOrder[nn, p]], {p, Prime[Range[100]]}]
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PROG
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(GAP) A000040:=Filtered([1..350], IsPrime);;
(PARI) a(n, {base=9}) = my(p=prime(n)); if(base%p, znorder(Mod(base, p)), 0) \\ Jianing Song, May 13 2024
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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