Abstract: In the present paper, the representative sequence of path lengths of a rooted tree and that of a tree is defined. It is found that between the treeg (resp. rooted trees) of order n-1 and that of order n, there exist simple relations between their sequences of path lengths. Making use of the relations, we obtain algorithms which generate the sequences of path lengths of all nonisomorphio rooted trees and all nonisomorphio trees. The storage required is less than that of the algorithm in[1], and the computer time required is less than that of the algorithm in[2].