A270104 Numbers k such that 3^k + k*2^k is prime.

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

Offset

1,2

Comments

a(17) > 30000. - Giovanni Resta, May 05 2016

Links

Table of n, a(n) for n=1..17.

Example

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

Mathematica

Select[Range[1000], PrimeQ[3^# + # * 2^#]&] (* Giovanni Resta, May 05 2016 *)

Prog

(MATLAB)
if isprime(3^n + n*2^n)
disp(n)
end
(PARI) is(n)=ispseudoprime(3^n+n*2^n) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A270102, A123924.

Sequence in context: A379211 A308918 A226819 * A063531 A063771 A064293

Adjacent sequences: A270101 A270102 A270103 * A270105 A270106 A270107

Keyword

nonn,more

Author

Vardan Semerjyan, Mar 11 2016

Extensions

a(15)-a(16) from Giovanni Resta, May 05 2016

a(17) from Michael S. Branicky, Jul 06 2024

Status

approved