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A137909 Least k such that k*(2^p-1)*(k*(2^p-1)+1)+1 is prime, where 2^p-1 runs through the Mersenne primes. 4
1, 2, 2, 3, 17, 8, 3, 6, 96, 9, 224, 33, 260, 1044, 2397, 3, 1487, 657, 9602, 2133, 18438, 93, 17273, 32583, 66539, 9632, 1431, 100440, 150857 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

1*(2^2-1)*(1*(2^2-1)+1)+1=13 prime, 2^2-1 first Mersenne prime, a(1)=1

2*(2^3-1)*(2*(2^3-1)+1)+1=211 prime, 2^3-1 second Mersenne prime, a(2)=2

CROSSREFS

Cf. A000043 (Mersenne exponents), A000668 (Mersenne primes).

Cf. A137906, A137907, A137908.

Sequence in context: A184840 A164022 A089751 * A035796 A049009 A101817

Adjacent sequences:  A137906 A137907 A137908 * A137910 A137911 A137912

KEYWORD

hard,more,nonn

AUTHOR

Pierre CAMI, Feb 22 2008

EXTENSIONS

a(27)-a(29) by Pierre CAMI, Oct 11 2014

STATUS

approved

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Last modified June 19 03:38 EDT 2021. Contains 345125 sequences. (Running on oeis4.)