%0 Journal Article %A Pingge Chen %A Zhousheng Mei %A Suijie Wang %T Inversion formulae on permutations avoiding 321 %J The electronic journal of combinatorics %D 2015 %V 22 %N 4 %U http://geodesic.mathdoc.fr/articles/10.37236/5451/ %R 10.37236/5451 %F 10_37236_5451