Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
191: | \[{4^{191}-1\over3}\] | 383 × 7068569257<10> × 39940132241<11> × 332584516519201<15> × 87274497124602996457<20> × 1046183622564446793972631570534611069350392574077339085483<58> |