

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
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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

Table of n, a(n) for n=1..18.
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



