A Note on the Structure of Groups of Order 2~np~2(n≥3)

In this paper,by using the special structures of some groups which are dihedral groups,or semi-dihedral groups,or quaternion groups,and some theorems in extension of groups,we obtain the classification of groups of order 2np2,Sylow p-subgroups of which are self-normalizer,and Sylow 2-subgroups are dihedral or semi-dihedral or quaternion groups.