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%I #13 Nov 25 2023 08:42:43
%S 2,4,6,8,12,14,18,36,68,152,212,324,1434,1592,1668,3338,7908,9662,
%T 27968,28116,33974,41774,66804,144518,162954,241032,366218,676592,
%U 991968
%N Numbers k such that 2^k - 23 is prime.
%C Note that for the values 2 and 4 the primes are negative.
%C a(22) > 41358. - _Jinyuan Wang_, Jan 20 2020
%C All terms are even. - _Elmo R. Oliveira_, Nov 24 2023
%H Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=2%5En-23">Search for 2^n-23</a>, PRP Top Records.
%e k = 6: 2^6 - 23 = 41 is prime.
%e k = 8: 2^8 - 23 = 233 is prime.
%t Do[ If[ PrimeQ[ 2^n - 23 ], Print[ n ] ], { n, 1, 15000} ]
%o (PARI) is(n)=ispseudoprime(2^n-23) \\ _Charles R Greathouse IV_, Jun 13 2017
%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), A096819 (d=19), A096820 (d=21), this sequence (d=23), A356826 (d=29).
%K nonn,more
%O 1,1
%A _Robert G. Wilson v_, Sep 16 2000
%E a(19)-a(21) from _Jinyuan Wang_, Jan 20 2020
%E a(22)-a(23) found by Henri Lifchitz, a(24)-a(27) found by Lelio R Paula, a(28)-a(29) found by Stefano Morozzi, added by _Elmo R. Oliveira_, Nov 24 2023
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