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A119591 Least k such that 2*n^k - 1 is prime. 1
1, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 2, 4, 1, 1, 2, 2, 1, 10, 1, 1, 6, 1, 2, 6, 1, 2, 136, 1, 1, 6, 6, 1, 6, 1, 1, 2, 2, 1, 2, 1, 2, 4, 1, 2, 4, 4, 1, 2, 1, 1, 44, 1, 1, 2, 1, 3, 2, 5, 3, 2, 2, 1, 4, 1, 768, 4, 1, 1, 52, 34, 2, 132, 1, 1, 14, 7, 1, 2, 2, 1, 8, 1, 2, 10, 1, 24, 60, 1, 1, 2, 3, 5, 2, 1, 1, 2, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

LINKS

Table of n, a(n) for n=2..100.

MATHEMATICA

f[n_] := Block[{k = 0}, While[ ! PrimeQ[2*n^k - 1], k++ ]; k ]; Table[f[n], {n, 2, 106}] (*Chandler*)

CROSSREFS

Cf. A119624.

Sequence in context: A183104 A183102 A178649 * A010125 A010324 A016525

Adjacent sequences:  A119588 A119589 A119590 * A119592 A119593 A119594

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jun 01 2006

EXTENSIONS

Corrected and extended by Ray Chandler, Jun 08 2006

STATUS

approved

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Last modified May 23 22:09 EDT 2013. Contains 225613 sequences.