Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 237: | \[{4^{237}-1\over3}\] | 3 × 7 × 1423 × 2687 × 49297 × 647011 × 13664473 × 202029703 × 1113491139767<13> × 23728823512345609279<20> × 31357373417090093431<20> × 201487636602438195784363<24> × 13775694692898492184744709216599873<35> |