Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
57: | \[{20^{57}-1\over19}\] | 19 × 229 × 421 × 75368484119<11> × 192696104561<12> × 1374892397251<13> × 207373637974370334920244263016739<33> |