gap> P:=SylowSubgroup(MathieuGroup(12),2);;
gap> P1:=EfficientNormalSubgroups(P)[1];;
gap> P2:=Intersection(DerivedSubgroup(P),P1);;
gap> P3:=Group(One(P));;
gap> R:=ResolutionNormalSeries([P,P1,P2,P3],9);
Resolution of length 9 in characteristic 
0 for &lt;permutation group with 64 generators&gt; . 

gap> Size(R);
[ 10, 60, 200, 532, 1238, 2804, 6338, 15528, 40649 ]
