	The automorphism group of PG(3,2) maps lines to lines. The number of automorphisms is given by finding the number of ways of selecting 4 points that are not coplanar; this works out to 15⋅14⋅12⋅8 = 20160 = 8!/2. It turns out that the automorphism group of PG(3,2) is isomorphic to the alternating group on 8 elements A.