  Skolem and Langford sequences and their many generalizations have
applications in numerous areas. The $\otimes_h$-product is a generalization of
the direct product of digraphs. In this paper we use the $\otimes_h$-product
and super edge-magic digraphs to construct an exponential number of Langford
sequences with certain order and defect. We also apply this procedure to
extended Skolem sequences.
