You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[3-[2-(3-hydroxypropyl)-5-(2-methylbutyl)-1,2,4-triazol-3-yl]phenyl]pyrrolidin-2-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N4O2
assistant