a(15) from http://oeis.org/A352736

177817^32768+177817^16384+177817^8192+177817^4096+177817^2048+177817^1024+177817^512+177817^256+177817^128+177817^64+177817^32+177817^16+177817^8+177817^4+177817^2+177817+1

Sieved to 10^9
Fermat PRP in bases 3 and 7, Lucas PRP in base 1+sqrt(13)

To be completed...