%I #6 Nov 20 2013 13:33:21
%S 0,0,1,1,0,8,1,2,0,7,0,5,0,203,1,3,2,3,0,3,3,0,2,1,0,1,2,7,0,1,1,5,2,
%T 1,8,2,0,501,3,1,8,3,0,1,2,0,0,1,22,3,1,4,5,0,2,4,11,1,6,1,2,5,0,3,0,
%U 7,1,0,1,18,8,3,13,5,6,2,3,34,1,2,3,4,19,5,6,4,1
%N Least k such that prime(n) + 2^(k+L) is a prime, where L is the length of binary representation of prime(n): L = A070939(A000040(n)). a(n)=-1 if no such k exists.
%C Prime(n) is in A065047 if and only if a(n)=0.
%Y Cf. A000040, A070939, A065047, A094076.
%K nonn,base,less
%O 2,6
%A _Alex Ratushnyak_, Nov 17 2013