

A200818


Numbers k such that (2^k  k)*2^k  1 is prime.


7




OFFSET

1,1


COMMENTS

The generalization of this sequence is possible with the primes of the form (b^n + k)*b^n + 1.


LINKS



EXAMPLE

4 is in the sequence because (2^4  4)*2^4  1 = 191 is prime.


MATHEMATICA

lst={}; Do[If[PrimeQ[(2^n  n)*2^n1], AppendTo[lst, n]], {n, 10^3}]; lst


PROG



CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



EXTENSIONS



STATUS

approved



