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%I #27 Jan 18 2020 11:00:25
%S 1,4,12,13,18,24,49,64,78,144,148,204,258,453,796,1309,1612,1812,3873,
%T 4348,6354,7996,8536,10128,11289,29544,32773,123114,130998,153417,
%U 168093,241602,487938,495732,555984,997537,1177629,1284429,1516368,1742689,2685873
%N Numbers k such that 243*2^k+1 is prime.
%H Jeppe Stig Nielsen, <a href="/A032498/b032498.txt">Table of n, a(n) for n = 1..42</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 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[243*2^# + 1] & ] (* _Robert Price_, Dec 20 2018 *)
%o (PARI) is(n)=ispseudoprime(243*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,hard
%O 1,2
%A _N. J. A. Sloane_.
%E a(31)-a(40) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 20 2018
%E a(41) (and b-file) from _Jeppe Stig Nielsen_, Jan 18 2020
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