... new class of admissible pairs of triangular sequences and provea bijection between the set of admissible pairs of triangular sequences of length nand the set of parking functions of length ... tree D = κn(p) it is equal, by Theorem 1.1, tothe number of inversions). Thus, by now we are able to describe conjecturally the sets of parking functions and trees of grading 0, 1, 2 and 3 using ... (n − 1 − r)+pr− (s + 1). By the choice of s,thenumbers + 1 is not an element of the electronic journal of combina torics 10 (2003), #R23 52. The set Y2consists of sequences (l0, ,ln−1)...