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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
OFFSET
1,2
COMMENTS
a(66) > 40000. - Robert Price, Mar 02 2015
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).
Sequence in context: A029661 A185439 A304458 * A018853 A218257 A193377
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