A323113 - OEIS

%I #9 Feb 16 2025 08:33:57

%S 7,27,31,43,79,169,193,241,511,987,1273,1807,2671,3327,3409,8469,

%T 12691,16465,50595,62155,154323,336465,479187,524997,641553,1048563

%N Numbers k such that 425*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="https://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(k->isprime(425*2^k+1),[$1..1000]); # _Muniru A Asiru_, Jan 05 2019

%t Select[Range[1000], PrimeQ[425*2^# + 1] &]

%K nonn,more,hard

%O 1,1

%A _Robert Price_, Jan 04 2019