%I

%S 2,5,15,17,17,83,173,357,629,179,2543,8067,5619,29027,38783

%N Next-to-smallest k such that 2^(2^n) - k is prime.

%o (PARI) a(n) = N = 2^(2^n); N - precprime(precprime(N)-1) \\ _Michel Marcus_, Jun 29 2013

%Y Cf. A058220.

%K nonn,hard,more

%O 1,1

%A _Warren D. Smith_, Nov 30 2000

%E a(15) from _Jinyuan Wang_, Jun 06 2020