A032411 - OEIS

%I #41 Dec 23 2024 10:39:22

%S 6,8,17,21,29,32,46,57,69,128,141,268,333,476,742,832,1173,1677,5068,

%T 9568,15453,34761,39992,41213,41852,93982,100748,102929,164069,286268,

%U 561012,582672,875878,1107008,3049038,3230548,3716758,4266441

%N Numbers k such that 123*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[123*2^# + 1] & ] (* _Robert Price_, Dec 17 2018 *)

%o (PARI) is(n)=ispseudoprime(123*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,hard,more

%O 1,1

%A _James R. Buddenhagen_

%E Extended by _Hugo Pfoertner_, Jul 02 2003

%E a(30)-a(34) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 17 2018

%E a(35) from _Jeppe Stig Nielsen_, Jan 19 2020

%E a(36)-a(38) from _Jeppe Stig Nielsen_, Dec 23 2024