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A057160 Smallest value of k for which the expression k*2^(2^n-1)-1 is prime. 0
1, 1, 1, 4, 1, 6, 1, 90, 111, 244, 139, 880, 309, 22263, 56083, 130141, 49905 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..16.

EXAMPLE

a(3)=4 because 4*2^(2^4-1)-1 = 4*2^15-1 = 4*32768-1 = 131071 which is prime.

CROSSREFS

Sequence in context: A032220 A032145 A032050 * A109915 A255198 A202521

Adjacent sequences:  A057157 A057158 A057159 * A057161 A057162 A057163

KEYWORD

nonn

AUTHOR

Steven Harvey, Sep 14 2000

STATUS

approved

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Last modified November 19 06:03 EST 2019. Contains 329310 sequences. (Running on oeis4.)