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A128395
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Numbers k such that k^2 divides 15^k-1.
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15
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1, 2, 4, 7, 8, 14, 16, 28, 56, 112, 136, 272, 452, 812, 904, 952, 1624, 1808, 1904, 3164, 3248, 6328, 11912, 12656, 15368, 18632, 23824, 27608, 30736, 37264, 47908, 55216, 60248, 83384, 91756, 95816, 102604, 107576, 113936, 120496, 130424, 166768
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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a={1}; For[n=1, n<200000, n++, If[PowerMod[15, n, n^2]==1, AppendTo[a, n]]]; a (* Stefan Steinerberger, Jun 10 2007 *)
Join[{1}, Select[Range[167000], PowerMod[15, #, #^2]==1&]] (* Harvey P. Dale, Sep 14 2020 *)
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PROG
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(PARI) is(k) = Mod(15, k^2)^k == 1; \\ Amiram Eldar, May 21 2024
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CROSSREFS
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Cf. A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128405, A128393, A128395, A128396, A128397, A128398, A128399, A128400, A128401, A128402, A128403, A128404.
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KEYWORD
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nonn,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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