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%I #40 Sep 08 2022 08:44:51
%S 1,4,5,7,9,12,16,17,41,124,128,129,187,209,276,313,397,899,1532,1613,
%T 1969,2245,2733,4585,4644,6712,6981,13344,17524,27124,29769,47337,
%U 55828,91008,94801,164901,179457,191337,200568,220992,686632,856865,1022168,1240067
%N Numbers k such that 21*2^k+1 is prime.
%H Jeppe Stig Nielsen, <a href="/A032360/b032360.txt">Table of n, a(n) for n = 1..48</a>
%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[21*2^#+1] &] (* _Amiram Eldar_, Dec 12 2018 *)
%o (PARI) is(n)=ispseudoprime(21*2^n+1) \\ _Charles R Greathouse IV_, Jun 06 2017
%o (Magma) [n: n in [0..5000] | IsPrime(21*2^n+1)]; // _Vincenzo Librandi_, Dec 12 2018
%K nonn,hard
%O 1,2
%A _James R. Buddenhagen_
%E More terms from _Hugo Pfoertner_, Jun 20 2003
%E Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013
%E a(47) from http://www.prothsearch.com/riesel1.html by _Robert Price_, Dec 12 2018
%E Terms moved from Data to b-file, and new term added to b-file, by _Jeppe Stig Nielsen_, Aug 29 2020
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