You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(3-pyridin-3-yl-1,2,4-oxadiazol-5-yl)ethyl 4-(4-methylphenyl)-4-oxobutanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19N3O4
assistant