A133856 Least number k > (2n-1) such that (2n-1)^k - 2 is prime, or 0 if no such number exists.

0, 4, 14, 8, 11, 22420, 78, 17, 24, 20, 25, 24, 63, 30, 42, 69, 128, 50, 119, 204, 2816, 76, 52, 288, 64, 66, 184, 153, 67, 268, 78, 210, 438, 295, 96, 74, 136, 128, 2900, 1898, 130, 92, 381, 106, 18626, 97, 98, 1650, 747, 109, 214, 113, 312, 354, 1702, 560, 2798, 123, 171, 554, 11210, 834, 208, 990, 9271

Offset: 1

Author

Alexander Adamchuk, Oct 01 2007

Keywords

• nonn

Comments

a(66) > 40000. - Robert Price, Mar 02 2015

Links

• Henri Lifchitz & Renaud Lifchitz: PRP Records. Probable Primes Top 10000.

Crossrefs

Cf. A128472 (smallest prime of the form (2n-1)^k - 2 for k > (2n-1), or 0 if no such number exists).

Cf. A084714 (smallest prime of the form (2n-1)^k - 2, or 0 if no such number exists).

Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128460, A128461.

Cf. A133858, A133982.

Formula

A128472(n) = (2n-1)^a(n) - 2 for n > 1.

Extensions

a(6) = 22420 was found by Rick L. Shepherd, Sep 29 2009

a(21)-a(44) from Max Alekseyev, Oct 04 2007

a(45)-a(65) from Robert Price, Mar 02 2015