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Numbers k such that 293*2^k + 1 is prime.
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%I #28 Sep 08 2022 08:45:00

%S 1,5,181,257,469,1541,2857,3521,14245,1049569

%N Numbers k such that 293*2^k + 1 is prime.

%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 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[5*10^3], PrimeQ[293*2^# + 1] &] (* _G. C. Greubel_, May 25 2018 *)

%o (PARI) is(n)=ispseudoprime(293*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%o (Magma) [n: n in [1..3000] | IsPrime(293*2^n+1)]; // _G. C. Greubel_, May 25 2018

%K hard,nonn,more

%O 1,2

%A _N. J. A. Sloane_, Dec 29 1999

%E a(10) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 22 2018