A032506 - OEIS

%I #24 Dec 21 2024 03:09:14

%S 38,70,3230,62918,82878,1282582,3094582,4395550

%N Numbers k such that 259*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[259*2^# + 1] & ] (* _Robert Price_, Dec 20 2018 *)

%o (PARI) is(n)=ispseudoprime(259*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K hard,nonn,more

%O 1,1

%A _N. J. A. Sloane_.

%E a(6) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 20 2018

%E a(7)-a(8) from _Jeppe Stig Nielsen_, Dec 21 2024