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Numbers k such that 2*3^k - 7 is prime.
8

%I #28 Jul 28 2024 10:59:07

%S 2,3,5,6,9,14,39,51,73,101,155,183,286,291,310,313,335,570,951,1011,

%T 1183,1930,2586,3423,6486,7791,11586,14290,18590,29595,35286,76311

%N Numbers k such that 2*3^k - 7 is prime.

%t Do[ If[ PrimeQ[ 2*3^n - 7 ], Print[n] ], {n, 1, 5700} ]

%o (PARI) is(n)=ispseudoprime(2*3^n-7) \\ _Charles R Greathouse IV_, May 22 2017

%o (Magma) [n: n in [1..1000] | IsPrime(2*3^n-7)]; // _Jinyuan Wang_, Jan 20 2020

%Y Cf. A059326 (2*3^k + 7 is prime).

%K nonn,more

%O 1,1

%A _Robert G. Wilson v_, Feb 15 2001

%E First term 0 removed by _Georg Fischer_, Aug 01 2019

%E a(27)-a(30) from _Jinyuan Wang_, Jan 20 2020

%E a(31) from _Michael S. Branicky_, May 20 2023

%E a(32) from _Michael S. Branicky_, Jul 28 2024