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A032356 Numbers k such that 13*2^k+1 is prime. 3


%S 2,8,10,20,28,82,188,308,316,1000,28280,38008,43856,88018,109258,

%T 114296,521306,562456,684560,1038896,1499876,1861732,4998362,5523860

%N Numbers k such that 13*2^k+1 is prime.

%H Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>

%H Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1.html">List of primes k.2^n + 1 for k < 300</a>

%H Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>

%H Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>

%H <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a>

%t Select[Range[1000], PrimeQ[13*2^#+1] &] (* _Amiram Eldar_, Dec 12 2018 *)

%o (PARI) is(n)=ispseudoprime(13*2^n+1) \\ _Charles R Greathouse IV_, May 22 2017

%Y Cf. A002257.

%K nonn,hard,more

%O 1,1

%A _James R. Buddenhagen_

%E Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013

%E a(23) from http://www.prothsearch.com/riesel1.html by _Robert Price_, Dec 12 2018

%E a(24) from _Jeppe Stig Nielsen_, Jan 24 2020

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Last modified February 27 10:31 EST 2020. Contains 332304 sequences. (Running on oeis4.)