Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 261: | \[{3^{261}-1\over2}\] | 13 × 59 × 757 × 28537 × 74821 × 20381027 × 32234893 × 150224123975857<15> × 138039202551886811051656379000595379114410970054365084709582198180836351736189201<81> |