By constructing a Gray map, constacyclic codes of arbitrary lengths over ring R =Z p m +vZ pmare studied, wherev 2=v. The structure of constacyclic codes over R and their dual codes are obtained. A necessary and sufficient condition for a linear code to be self-dual constacyclic is given. In particular,(1 +(v +1)ap)-constacyclic codes over R are classified in terms of generator polynomial, where a is a unit of Z m.
By constructing a Gray map, constacyclic codes of arbitrary lengths over ring R = Zpm + vZpm are studied, where v2 = v. The structure of constacyclic codes over R and their dual codes are obtained. A necessary and sufficient condition for a linear code to be self-dual constacyclic is given. In particular, (1 + (v + 1)αp)-constacyclic codes over R are classified in terms of generator polynomial, where α is a unit of Zpm.