n!!!! + 1
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
281: | \[281!!!!+1\] | 2 × 353 × 112591769002458797<18> × 52696905038584308971860187<26> × 297682085395601417244354592950284321431307809<45> × 42822760304271913906142094426202965380970252427945021<53> |