Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
56: | \[{20^{56}-1\over19}\] | 3 × 72 × 29 × 71 × 197 × 401 × 617 × 827 × 1009 × 10529 × 14561 × 28393 × 32719 × 160001 × 1424354653 × 5417928377<10> × 175184754697<12> |