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A319295
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Numbers k such that k^2 + 2 divides 2^k - 2.
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0
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OFFSET
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1,2
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COMMENTS
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Is this sequence infinite?
Are there other prime terms except a(4) = 601021?
Let f(n) be the smallest k > 1 such that k^2 + n divides 2^k - 2. f(0) = 1093 (cf. A001220), f(1) = 95 and f(2) = a(2) = 166751.
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LINKS
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MATHEMATICA
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Select[Range[10^7], IntegerQ[(2^# - 2) / (#^2 + 2)] &] (* Vincenzo Librandi, Sep 21 2018 *)
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PROG
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(PARI) isok(n) = Mod(2, n^2+2)^n==2;
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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STATUS
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approved
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