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%I #30 Apr 03 2023 10:36:09
%S 3,393050634124102232869567034555427371542904833
%N Cullen primes: primes of the form n*2^n+1.
%C The next term is too large to display here, having 1423 digits. See A005849.
%H Ray Ballinger, <a href="http://web.archive.org/web/20161028015144/http://www.prothsearch.net/cullen.html">Cullen Primes: Definition and Status</a>
%H Chris K. Caldwell, <a href="https://t5k.org/top20/page.php?id=6">Cullen Primes</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CullenNumber.html">Cullen Number</a>
%F a(n) = A002064(A005849(n)).
%e 1 * 2^1 + 1 = 3, which is prime.
%e 141 * 2^141 + 1 = 393050634124102232869567034555427371542904833, which is also prime.
%e The third Cullen prime is approximately 2.677114856136697933736444 * 10^1422.
%t Select[Table[n * 2^n + 1, {n, 5000}], PrimeQ] (* _Harvey P. Dale_, Dec 14 2014 *)
%Y See A005849 for the corresponding n.
%K nonn,nice,bref
%O 1,1
%A _N. J. A. Sloane_, Dec 30 1999
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