Found with PFGW Version 3.6.0

1615^4176-4176^1615 is 2-PRP! (8.7815s+0.0021s)
1615^4176-4176^1615 is 3-PRP! (8.6569s+0.0022s)
1615^4176-4176^1615 is 5-PRP! (8.6749s+0.0017s)
1615^4176-4176^1615 is 7-PRP! (8.6417s+0.0018s)
1615^4176-4176^1615 is 11-PRP! (8.6989s+0.0020s)

Primality testing 1615^4176-4176^1615 [N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 11
Running N+1 test using discriminant 17, base 2+sqrt(17)
Calling N+1 BLS with factored part 0.10% and helper 0.09% (0.40% proof)
1615^4176-4176^1615 is Fermat and Lucas PRP! (41.6731s+0.0030s)

To be completed...