You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[acetyl(methyl)amino]-N-(2,6-dimethyl-2,3-dihydro-1H-inden-1-yl)piperidine-1-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H29N3O2
assistant