The reason this PRP s form is so strange is that it is based on "mock-rational numbers" -- those that exhibit patterns in their digits. Its decimal expansion consists of repeating 518s and 925s, along with single repeating digits, and other patterns separated by “random” strings.

Resuming input file MOCK4.txt at line 1
[N-1/N+1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 11
Running N-1 test using base 13
Running N+1 test using discriminant 19, base 6+sqrt(19)
Running N+1 test using discriminant 19, base 11+sqrt(19)
5185185185185185....000000000000000000449 is Fermat and Lucas PRP!

To be completed...