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Numbers k such that 455*2^k+1 is prime.
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%I #12 Feb 16 2025 08:33:57

%S 1,5,9,15,17,37,111,139,185,287,297,561,705,769,1187,1537,1795,2571,

%T 3391,9367,11355,11871,13739,15381,30201,34227,40515,201207,220397,

%U 247841,461215,599531,689757,897885,1289501,1493715,1779315,3981067

%N Numbers k such that 455*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>.

%t Select[Range[1000], PrimeQ[455*2^# + 1] &]

%K nonn,more,hard,changed

%O 1,2

%A _Robert Price_, Jan 06 2019

%E a(38) from _Jeppe Stig Nielsen_, Dec 18 2024