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%I #18 Jul 08 2024 14:59:38
%S 1,3,9,11,15,17,24,41,68,72,641,716,1139,1200,1661,3339,5181,68769
%N Numbers k such that 2*3^k + 7 is prime.
%C a(18) > 26240. - _Jinyuan Wang_, Jan 20 2020
%C a(19) > 100000. - _Michael S. Branicky_, Jul 08 2024
%t Do[ If[ PrimeQ[ 2*3^n + 7 ], Print[n] ], {n, 0, 10000} ]
%o (PARI) is(n)=ispseudoprime(2*3^n+7) \\ _Charles R Greathouse IV_, Jun 13 2017
%o (Magma) [n: n in [0..1000] | IsPrime(2*3^n+7)]; // _Jinyuan Wang_, Jan 20 2020
%Y Cf. A059454 (2*3^k - 7 is prime).
%K nonn,more
%O 1,2
%A _Robert G. Wilson v_, Feb 15 2001
%E a(18) from _Michael S. Branicky_, Jul 07 2024