You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [2-[1-(3,4-dimethylphenyl)ethylamino]-2-oxoethyl] 1-ethylsulfonylpiperidine-4-carboxylate by IUPAC nomenclature, provide its molecular formula.
user
C20H30N2O5S
assistant