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A128472 a(n) = smallest prime of the form (2n-1)^k - 2 for k>(2n-1), or 0 if no such number exists. 13

%I

%S 0,79,6103515623,5764799,31381059607

%N a(n) = smallest prime of the form (2n-1)^k - 2 for k>(2n-1), or 0 if no such number exists.

%C a(6) = 11^22420 - 2 was found by Rick L. Shepherd 09/29/2007. It has 23349 decimal digits and it is too large to include.

%C a(7)-a(12) = {771936328432730777189183517369830159827426282764863750131729657829597399846468418688727, 98526125335693359373, 339448671314611904643504117119, 37589973457545958193355599, 1136272165922724266740722458520499, 480250763996501976790165756943039}.

%H Henri Lifchitz & Renaud Lifchitz : <a href="http://www.primenumbers.net/prptop/prptop.php">PRP Records. Probable Primes Top 10000</a>.

%Y Cf. A084714 = smallest prime of the form (2n-1)^k - 2, or 0 if no such number exists.

%Y Cf. A133856 = least number k>(2n-1) such that (2n-1)^k - 2 is prime, or 0 if no such number exists.

%Y Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128460, A128461. Cf. A133858, A133982.

%K nonn

%O 1,2

%A _Alexander Adamchuk_, Mar 14 2007, Oct 01 2007

%E Edited by _Max Alekseyev_, Sep 18 2009

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Last modified April 21 14:46 EDT 2021. Contains 343154 sequences. (Running on oeis4.)