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A133856 Least number k>(2n-1) such that (2n-1)^k - 2 is prime, or 0 if no such number exists. 1
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 (list; graph; refs; listen; history; text; internal format)
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

more,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

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Last modified June 24 22:00 EDT 2019. Contains 324337 sequences. (Running on oeis4.)