You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(3-ethyl-1,2,4-oxadiazol-5-yl)-N-[1-(7-methoxy-1-benzofuran-2-yl)ethyl]butanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H23N3O4
assistant