20F22 5 locally nilpotent radical 20E34 4 20F50 4 finite special rank 4 locally nilpotent residual 4 periodic group 4 soluble group 4 transitively normal subgroups 4 20F16; Secondary 20E25 2 20F16; Secondary: 20E25 2 Primary 20E15 2 Primary: 20E15 2 (generalized) radical group 1 20F16 1 20F18 1 20F19 1 \(GNA\)-subgroup 1 abnormal subgroup 1 locally finite radical 1 normal subgroup 1 pronormal subgroup 1 self-normalizing subgroup 1