Base 31 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 81: | \[{31^{81}-1\over30}\] | 34 × 331 × 2593 × 3637 × 13933 × 81343 × 477739 × 6757669 × 7822981 × 1836205027201<13> × 126901881805771<15> × 124796720050174992115146031610052568212932455637390989<54> |