Base 28 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
61: | \[{28^{61}-1\over27}\] | 584814157619<12> × 108152440326426913<18> × 11071894699054087656875578952698529117084924031399006144383<59> |