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Numbers k such that 237*2^k+1 is prime.
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%I #25 Dec 21 2024 03:39:26

%S 4,10,52,58,59,68,82,115,247,647,2338,2627,4415,8410,17098,38434,

%T 42739,59140,100627,104372,127363,137767,173551,234082,243772,585403,

%U 1710490,4153348,5291999,5315983

%N Numbers k such that 237*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 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[237*2^# + 1] & ] (* _Robert Price_, Dec 19 2018 *)

%o (PARI) is(n)=ispseudoprime(237*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,hard,more

%O 1,1

%A _N. J. A. Sloane_.

%E a(19)-a(27) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 19 2018

%E a(28)-a(30) from _Jeppe Stig Nielsen_, Dec 21 2024