Found with PFGW Version 3.6.0

39^20728-38 is 2-PRP! (15.9405s+0.0028s)
39^20728-38 is 3-PRP! (15.8453s+0.0027s)
39^20728-38 is 5-PRP! (16.0048s+0.0027s)
39^20728-38 is 7-PRP! (15.9565s+0.0025s)
39^20728-38 is 11-PRP! (15.8374s+0.0039s)

Primality testing 39^20728-38 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 2
Running N+1 test using discriminant 5, base 1+sqrt(5)
Calling N-1 BLS with factored part 0.31% and helper 0.00% (0.93% proof)
39^20728-38 is Fermat and Lucas PRP! (115.6207s+0.0027s)

To be completed...