The notion of partitional graphs, a subclass of sequential graphs, is introduced, and the cartesian product of a partitional graph and K 2 is shown to be partitional. Every sequential graph is harmonious and felicitous. The partitional property of some bipartite graphs including the n-dimensional cube Q n is studied, and thus this paper extends what was known about the sequentialness, harmoniousness and felicitousness of such graphs.