n!! + 1
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| * 291: | \[291!!+1\] | 22 × 655744811 × 41347758659<11> × 8472095838611<13> × [532176046227298192993666394066242626493427315490172082387819544434444890840124703159582469895589535178176561151040414704437407092806330371764670452501339064226173613965739297857329277473457352086551609114122375251384321943866626135300310846682094266699993682639171<264>] |