Cameron et al. recently presented an algorithm for generating all spanning trees of a fan graph that fulfill the so-called pivot Gray code property in O(1)-amortized time. They also presented algorithms for ranking and unranking a spanning tree in the listing in O(n) time using O(n) space. This paper first observes that all spanning trees of a fan graph can be naturally represented by integer sequences with regular properties. We propose a simple algorithm for generating spanning-tree sequences in lexicographic order in O(1)-amortized time according to these properties. Additionally, based on the lexicographic order, we develop ranking and unranking algorithms in O(n)-time using n+O(1) space.