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%I #28 Aug 04 2024 19:52:24
%S 0,2,4,6,8,16,18,26,30,42,52,54,60,98,138,148,164,180,188,198,232,268,
%T 366,494,556,636,700,830,908,2164,5764,9854,10384,17550,20236,32820,
%U 42372,77466,106562
%N Numbers k such that 7*2^k - 5 is prime.
%C a(36) > 30000. - _Jinyuan Wang_, Feb 01 2020
%t Do[ If[ PrimeQ[ 7*2^n - 5 ], Print[ n ] ], {n, 0, 5371} ]
%t Select[Range[0, 10000], PrimeQ[(7*2^# - 5)] &] (* _Vincenzo Librandi_, Sep 29 2012 *)
%o (PARI) is(n)=ispseudoprime(7*2^n-5) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A058595 (7*2^k + 5 is prime).
%K nonn,more
%O 1,2
%A _Robert G. Wilson v_, Dec 26 2000
%E a(31)-a(32) from _Vincenzo Librandi_, Sep 29 2012
%E a(33)-a(35) from _Jinyuan Wang_, Feb 01 2020
%E a(36)-a(37) from _Michael S. Branicky_, May 19 2023
%E a(1)=0 inserted and a(38)-a(39) from _Michael S. Branicky_, Jul 27 2024
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