A generalized repunit probable prime in base 2617. Note that the base (2617) and the exponent (6271) use the same decimal digits.
The top 20 (probable) primes for the least smallest repunit prime with at least 3 1s in bases 2<=b<=1024 are: (sorted by exponent)
(152^270217-1)/151, (18^25667-1)/17, (333^9743-1)/332
(536^6653-1)/535, (922^5987-1)/921, (469^5987-1)/468
(702^5897-1)/701, (1012^5749-1)/1011, (683^5483-1)/682
(230^5333-1)/229, (739^5087-1)/738, (898^4951-1)/897
(972^4937-1)/971, (994^4723-1)/993, (499^4691-1)/498
(895^4507-1)/894, (91^4421-1)/90, (844^4289-1)/843
(51^4229-1)/50, (716^4133-1)/715

To be completed...