Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
72: | \[{20^{72}-1\over19}\] | 33 × 7 × 13 × 37 × 73 × 127 × 307 × 401 × 421 × 12277 × 24877 × 31177 × 69481 × 160001 × 821113 × 4468393 × 64008001 × 4450002049<10> × 51433451961886233152209<23> |