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%I #34 Dec 12 2020 06:15:50
%S 8,12,44,84,96,228,264,320,732,788,1808,7928,12264,37784,59196,91112,
%T 112208,168716,251184,264632,272052,513020,636564,674360
%N Numbers k such that 121*2^k+1 is prime.
%C 9584444 is also a term (cf. PrimeGrid, 2020). - _Felix Fröhlich_, Dec 10 2020
%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 PrimeGrid, <a href="http://www.primegrid.com/download/27121-9584444.pdf">Announcement of 9584444</a>, 2020.
%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[121*2^# + 1] & ] (* _Robert Price_, Dec 17 2018 *)
%o (PARI) is(n)=ispseudoprime(121*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A050586.
%K nonn,hard,more
%O 1,1
%A _James R. Buddenhagen_
%E Extended by _Hugo Pfoertner_, Jul 02 2003
%E a(20)-a(24) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 17 2018
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