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Search: id:A137908
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| A137908 |
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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. |
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4
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| 1, 3, 1, 7, 8, 38, 13, 4, 16, 3, 42, 24, 434, 84, 160, 579, 475, 529, 2450, 2644, 3928, 558, 13680, 71, 46, 1408, 3003
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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1*(2^2-1)*(1*(2^2-1)+1)-1=11 prime, 2^2-1 first Mersenne prime, k(1)=1
3*(2^3-1)*(3*(2^3-1)+1)-1=461 prime, 2^3-1 second Mersenne prime, k(2)=3
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CROSSREFS
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Cf. A137906, A137907, A137909.
Sequence in context: A091039 A120472 A121370 this_sequence A019639 A011207 A087129
Adjacent sequences: A137905 A137906 A137907 this_sequence A137909 A137910 A137911
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KEYWORD
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hard,more,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Feb 22 2008
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