Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 138: | \[{4^{138}-1\over3}\] | 3 × 5 × 7 × 13 × 47 × 139 × 277 × 1013 × 1657 × 30269 × 178481 × 2796203 × 168749965921<12> × 5415624023749<13> × 10052678938039<14> × 70334392823809<14> |