n!!!! + 1
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
254: | \[254!!!!+1\] | 1423 × 5273 × 13451161639<11> × 586589416998629866817<21> × 690627901111696790991839<24> × 1366531469741097467214224033<28> × 54390462619220495763544324215590074399<38> |