A194636 -id:A194636 - cp's OEIS frontend

A194639 Indices of records in A194591 when it is restricted to odd indices.

1, 5, 13, 47, 59, 109, 241, 335, 1109, 1373, 1447, 14893, 52267, 56543, 649603, 838441, 8840101, 16935761, 100604513, 118373279, 270704167, 1355477231

Offset: 1

Arkadiusz Wesolowski, Aug 31 2011

Integers for which the smallest k in A194591 such that (2*n-1)*2^k - 1 or (2*n-1)*2^k + 1 is prime (A194638) increases.

A194637 gives the record values of A194636.

Wilfrid Keller, personal communication, 2010.

Chris K. Caldwell, The List of Largest Known Primes, 1355477231 * 2^356981 + 1
Carlos Rivera, Problem 30

Cf. A194591, A194600, A194603, A194606, A194607, A194608, A194635, A194636, A194637, A194638.
Cf. A064699, A076335, A180247, A217892.
Cf. A217892 (indices of records of unrestricted A194591)

l = -1; Flatten[Table[n = 2*n - 1; k = 0; While[! PrimeQ[n*2^k - 1] && ! PrimeQ[n*2^k + 1], k++]; If[k > l, l = k; n, {}], {n, 10^5}]] (* Arkadiusz Wesolowski, Sep 04 2011 *)

a(22) was found in 2002 by Wilfrid Keller.

Definition corrected by Max Alekseyev and Farideh Firoozbakht, Oct 16 2014

A194607 Record values in A194606.

Original entry on oeis.org

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

Offset: 1

Arkadiusz Wesolowski, Aug 30 2011

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.

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

Wilfrid Keller, personal communication, 2010.

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

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

Cf. A103963, A103964, A076335, A180247.

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 *)

cp's OEIS Frontend

A194639 Indices of records in A194591 when it is restricted to odd indices.

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