Generalized repunit prime (base 245).
For base 241, I found R17, R31.
For base 242, I found R19, R541.
For base 243, no possible prime.
For base 244, I found R3331, R5099.
For base 245, I found R3, R9277.
For base 246, I found R3, R37, R251.

To be completed...