1st PRP for 2^n-255463.

Sieved to P=200G.

Primality testing 2^177641-255463 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 137
Running N+1 test using discriminant 163, base 2+sqrt(163)
Calling N+1 BLS with factored part 0.02% and helper 0.01% (0.08% proof)
2^177641-255463 is Fermat and Lucas PRP! (3250.0986s+0.0093s)

To be completed...