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 A319295 Numbers k such that k^2 + 2 divides 2^k - 2. 0
 1, 166751, 538085, 601021, 1078445, 1579201 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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. The next term, if it exists, is > 10^9. - Vaclav Kotesovec, Oct 23 2018 a(7) > 1.9*10^11, if it exists. - Giovanni Resta, Oct 29 2018 LINKS MATHEMATICA Select[Range[10^7], IntegerQ[(2^# - 2) / (#^2 + 2)] &] (* Vincenzo Librandi, Sep 21 2018 *) PROG (PARI) isok(n) = Mod(2, n^2+2)^n==2; CROSSREFS Cf. A001220. Sequence in context: A186919 A185803 A250931 * A235846 A187170 A047829 Adjacent sequences:  A319292 A319293 A319294 * A319296 A319297 A319298 KEYWORD nonn,hard,more AUTHOR Altug Alkan, Sep 16 2018 STATUS approved

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Last modified April 23 10:51 EDT 2021. Contains 343204 sequences. (Running on oeis4.)