Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #18 Feb 05 2020 08:26:12
%S 3,7,21,23,29,35,53,87,91,95,115,165,179,233,367,419,609,791,2937,
%T 3713,4087,5071,6497,30011,30783,32861,48299,60155,143623,293525,
%U 465959,567161,975215,1024223,1106333,1285643,1597089,2233655,2733989,2840155
%N Numbers k such that 305*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="http://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>
%t Select[Range[1000], PrimeQ[305*2^# + 1] &] (* _Robert Price_, Dec 30 2018 *)
%Y Cf. A002255, A050527.
%K nonn,more,hard
%O 1,1
%A _Robert Price_, Dec 30 2018
%E a(38)-a(39) from _Jeppe Stig Nielsen_, Dec 27 2019
%E a(40) from _Jeppe Stig Nielsen_, Feb 05 2020