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 A129962 Primes of the form 2^n + n. 5

%I

%S 3,11,37,521,32783,549755813927,37778931862957161709643,

%T 2417851639229258349412433,618970019642690137449562201,

%U 266998379490113760299377713271194014325338065294581596243380200977777465722580068752870260867389

%N Primes of the form 2^n + n.

%C It is convenient, although not necessary, to let n be an odd number since n even => 2^n + n is even > 2. Conjecture: There is an infinite number of primes in this sequence. If n is prime we have A057664.

%H Hugo Pfoertner, <a href="/A129962/b129962.txt">Table of n, a(n) for n = 1..16</a>

%e for n = 3, 2^3+3=11 prime and the second entry.

%t Select[Table[2^n+n,{n,600}],PrimeQ[#]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 18 2011*)

%o (PARI) f(n) = forstep(x=1,n,2,y=2^x+x;if(isprime(y),print1(y",")))

%o (MAGMA) [a: n in [0..400] | IsPrime(a) where a is 2^n + n]; // _Vincenzo Librandi_, Jul 25 2019

%Y Cf. A052007 (values of n), A057664, A081296.

%K nonn

%O 1,1

%A _Cino Hilliard_, Jun 10 2007

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Last modified February 27 03:30 EST 2020. Contains 332299 sequences. (Running on oeis4.)