Negacyclic codes of length 4ps over Fpm+uFpm and their duals

For any odd prime p, negacyclic codes of length 4ps over the finite commutative chain ring Fpm+uFpm are investigated. The algebraic structures of such codes are classified and completely determined. As an application, the number of codewords and the dual of each negacyclic code are obtained. Simpler structure of cyclic codes of length 4ps over Fpm+uFpm is also noted. Among others, some self-dual negacyclic and cyclic codes of length 4ps over Fpm+uFpm are provided.