20F22 3 locally nilpotent radical 3 20E34 2 20F50 2 finite special rank 2 locally nilpotent residual 2 periodic group 2 soluble group 2 transitively normal subgroups 2 (generalized) radical group 1 20F16 1 20F16; Secondary 20E25 1 20F16; Secondary: 20E25 1 20F18 1 20F19 1 Primary 20E15 1 Primary: 20E15 1 \(GNA\)-subgroup 1 abnormal subgroup 1 locally finite radical 1 normal subgroup 1 pronormal subgroup 1 self-normalizing subgroup 1