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A129962
Primes of the form 2^k + k.
7
3, 11, 37, 521, 32783, 549755813927, 37778931862957161709643, 2417851639229258349412433, 618970019642690137449562201, 266998379490113760299377713271194014325338065294581596243380200977777465722580068752870260867389
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
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
Cf. A052007 (values of n), A057664, A081296.
Sequence in context: A183511 A307800 A265796 * A026361 A006189 A092201
KEYWORD
nonn
AUTHOR
Cino Hilliard, Jun 10 2007
STATUS
approved