A194607 Record values in A194606.

0, 1, 2, 4, 5, 6, 11, 17, 20, 28, 70, 99, 150, 726, 7431, 22394, 85461, 191207

Offset

1,3

Comments

The index sequence of this one is 1, 3, 6, 15, 17, 29, 53, 115, 186, 220, 229, 1886, 5344, 5736, 66774, 1087403, 14747671, 158018119.

a(17) was found in 2000 by Wilfrid Keller and a(18) was found in 2003 by Patrick De Geest.

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

Example

A194606(53) = 11 since A194606(115) = 17 is the next record value.

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, {}], {n, 10^4}]] (* Arkadiusz Wesolowski, Sep 04 2011 *)

Crossrefs

Cf. A194591, A194600, A194603, A194606, A194608, A194635, A194636, A194637, A194638, A194639.

Cf. A103963, A103964, A076335, A180247.

Sequence in context: A192582 A101951 A171166 * A194637 A194600 A255543

Adjacent sequences: A194604 A194605 A194606 * A194608 A194609 A194610

Keyword

more,nonn

Author

Arkadiusz Wesolowski, Aug 30 2011

Status

approved