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

1,2

Comments

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

Links

Table of n, a(n) for n=1..65.

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

Formula

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

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.

Sequence in context: A029661 A185439 A304458 * A018853 A218257 A193377

Adjacent sequences: A133853 A133854 A133855 * A133857 A133858 A133859

Keyword

nonn

Author

Alexander Adamchuk, Oct 01 2007

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

Status

approved