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%I #29 Nov 28 2023 12:53:03
%S 5,7,11,15,19,21,31,39,67,69,85,157,171,191,255,291,379,3669,4551,
%T 9531,13119,14211,20647,233965,337267,534429,535415,816039,991715
%N Numbers k such that 2^k - 19 is prime.
%C All terms are odd since for even k, 2^k - 19 is divisible by 3.
%C a(26) > 5*10^5. - _Tyler NeSmith_, Apr 16 2022
%H Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=2%5En-19">Search for 2^n-19</a>, PRP Top Records.
%e 2^7 - 19 = 128 - 19 = 109, a prime, so 7 is a term of the sequence.
%t Select[Range[5,20000],PrimeQ[2^#-19]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 27 2011*)
%Y Cf. A096502.
%Y Cf. Sequences of numbers k such that 2^k - d is prime: A000043 (d=1), A050414 (d=3), A059608 (d=5), A059609 (d=7), A059610 (d=9), A096817 (d=11), A096818 (d=13), A059612 (d=15), A059611 (d=17), this sequence (d=19), A096820 (d=21), A057220 (d=23), A356826 (d=29).
%K nonn,more
%O 1,1
%A _Labos Elemer_, Jul 13 2004
%E a(22)-a(23) from _Max Alekseyev_, Feb 10 2012
%E a(24)-a(25) from Lelio R Paula, added by _Max Alekseyev_, Oct 24 2013
%E a(26)-a(29) found by Stefano Morozzi, added by _Alois P. Heinz_, Aug 29 2022
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