A270104 - OEIS

%I #21 Jul 07 2024 01:14:07

%S 1,2,7,8,13,43,55,59,145,149,545,2468,4049,4055,15653,22765,99932

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

%C a(17) > 30000. - _Giovanni Resta_, May 05 2016

%e n = 2 is a term since 3^2 + 2*2^2 = 17 is prime.

%t Select[Range[1000], PrimeQ[3^# + # * 2^#]&] (* _Giovanni Resta_, May 05 2016 *)

%o (MATLAB)

%o if isprime(3^n + n*2^n)

%o disp(n)

%o end

%o (PARI) is(n)=ispseudoprime(3^n+n*2^n) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A270102, A123924.

%K nonn,more

%O 1,2

%A _Vardan Semerjyan_, Mar 11 2016

%E a(15)-a(16) from _Giovanni Resta_, May 05 2016

%E a(17) from _Michael S. Branicky_, Jul 06 2024