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 A194635 Indices of records in A194591 restricted to prime indices. 13
 2, 5, 13, 47, 59, 109, 241, 631, 1109, 1373, 1447, 16229, 52267, 56543, 838441, 16935761, 270704167, 3296757029 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Integers for which the smallest k in A194591 such that prime(n)*2^k - 1 or prime(n)*2^k + 1 is prime (A194608) increases. a(19) > 10^10. A194607 gives the record values of A194606. REFERENCES Wilfrid Keller, personal communication, 2010. LINKS Chris K. Caldwell, The List of Largest Known Primes, 270704167 * 2^85461 - 1 Chris K. Caldwell, The List of Largest Known Primes, 3296757029 * 2^191207 + 1 Carlos Rivera, Problem 30 MATHEMATICA l = -1; Flatten[Table[p = Prime[n]; k = 0; While[! PrimeQ[p*2^k - 1] && ! PrimeQ[p*2^k + 1], k++]; If[k > l, l = k; p, {}], {n, 10^4}]] (* Arkadiusz Wesolowski, Sep 04 2011 *) CROSSREFS Cf. A194591, A194600, A194603, A194606, A194607, A194608, A194636, A194637, A194638, A194639. Cf. A064699, A076335, A180247, A217892. Sequence in context: A085632 A111563 A079573 * A212821 A067021 A269068 Adjacent sequences:  A194632 A194633 A194634 * A194636 A194637 A194638 KEYWORD more,nonn AUTHOR Arkadiusz Wesolowski, Aug 31 2011 EXTENSIONS a(17) was found in 2000 by Wilfrid Keller a(18) was found in 2003 by Patrick De Geest Edited by Max Alekseyev, Oct 14 2012 Edited by Arkadiusz Wesolowski, Sep 11 2013 STATUS approved

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Last modified May 8 02:26 EDT 2021. Contains 343652 sequences. (Running on oeis4.)