n!!!! + 1
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 261: | \[261!!!!+1\] | 2 × 283 × 14382427 × 22671965995970219<17> × 3524343286480786401429855397693559372716481385337799<52> × 54195212730568573982806320467354554092450518283522503<53> |