Primality testing 27708^28913-28913^27708 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 5
Running N+1 test using discriminant 17, base 1+sqrt(17)
Calling N+1 BLS with factored part 0.00% and helper 0.00% (0.01% proof)
27708^28913-28913^27708 is Fermat and Lucas PRP! (640.9076s+0.0025s)

Sieved with xyyxsieve

To be completed...