OFFSET
1,1
COMMENTS
It is convenient, although not necessary, to let k be an odd number since k even => 2^k + k is even > 2.
Conjecture: sequence is infinite.
If k is prime we have A057664.
LINKS
Hugo Pfoertner, Table of n, a(n) for n = 1..16
EXAMPLE
For k = 3, 2^3 + 3 = 11 prime, so 11 is a term.
MATHEMATICA
Select[Table[2^n+n, {n, 600}], PrimeQ[#]&] (* Vladimir Joseph Stephan Orlovsky, Feb 18 2011 *)
PROG
(PARI) f(n) = forstep(x=1, n, 2, y=2^x+x; if(isprime(y), print1(y", ")))
(Magma) [a: n in [0..400] | IsPrime(a) where a is 2^n + n]; // Vincenzo Librandi, Jul 25 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Cino Hilliard, Jun 10 2007
STATUS
approved