You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-(2-methoxyethyl)-3,5-dimethylpiperazin-1-yl]-2-[3-(4-methoxyphenyl)-1,2,4-oxadiazol-5-yl]ethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H28N4O4
assistant