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
Examples
n = 2 is a term since 3^2 + 2*2^2 = 17 is prime.
Programs
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MATLAB
if isprime(3^n + n*2^n) disp(n) end
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Mathematica
Select[Range[1000], PrimeQ[3^# + # * 2^#]&] (* Giovanni Resta, May 05 2016 *)
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PARI
is(n)=ispseudoprime(3^n+n*2^n) \\ Charles R Greathouse IV, Jun 13 2017
Extensions
a(15)-a(16) from Giovanni Resta, May 05 2016
a(17) from Michael S. Branicky, Jul 06 2024
Comments