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 A137907 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. 3
 1, 1, 9, 6, 9, 24, 4, 7, 28, 70, 73, 121, 511, 106, 343, 2169, 1423, 2146, 5736, 4444, 2484, 2310, 2679, 25623, 2481, 39213 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE 1*(2^2-1)*(1*(2^2-1)-1)+1=7 prime, 2^2-1 first Mersenne prime, a(1)=1; 1*(2^3-1)*(1*(2^3-1)-1)+1=43 prime, 2^3-1 second Mersenne prime, a(2)=1. CROSSREFS Cf. A137906, A137908, A137909. Sequence in context: A019790 A033186 A146486 * A070164 A063602 A180572 Adjacent sequences:  A137904 A137905 A137906 * A137908 A137909 A137910 KEYWORD nonn,hard,more AUTHOR Pierre CAMI, Feb 22 2008 EXTENSIONS Corrected by Pierre CAMI, Jun 16 2012 STATUS approved

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Last modified July 26 10:48 EDT 2021. Contains 346294 sequences. (Running on oeis4.)