1st PRP for 2^n-428563.

Sieved to P=200G.

Primality testing 2^38489-428563 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 41
Running N+1 test using discriminant 47, base 2+sqrt(47)
Calling N+1 BLS with factored part 0.07% and helper 0.02% (0.22% proof)
2^38489-428563 is Fermat and Lucas PRP! (72.6180s+0.0083s)

To be completed...