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Numbers k such that 343*2^k+1 is prime.
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%I #6 Dec 31 2018 20:25:53

%S 2,20,22,46,58,226,3760,7060,16192,22018,35576,103952,113326,120716,

%T 285122,543148,785510,1033126

%N Numbers k such that 343*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/riesel1a.html">List of primes k.2^n + 1 for 300 < k < 600</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 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ProthPrime.html">Proth Prime</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>

%p select(n->isprime(343*2^n+1),[$1..1000]); # _Muniru A Asiru_, Dec 31 2018

%t Select[Range[1000], PrimeQ[343*2^# + 1] &] (* _Robert Price_, Dec 31 2018 *)

%Y Cf. A002255, A050527.

%K nonn,more,hard

%O 1,1

%A _Robert Price_, Dec 31 2018