%N Conjectured least number k such that k^k - n^n is prime.
%C The zero entries are only conjectural.
%C The a(n) = 0 entries have been checked up to k = 7500.
%o (PARI) a(n)=k=1;while(k<7500,if(ispseudoprime(k^k-n^n),return(k));k++)
%Y Cf. A249570.
%A _Derek Orr_, Nov 02 2014