You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[3-[4-[(3-fluoro-4-methoxyphenyl)methyl]piperazine-1-carbonyl]piperidin-1-yl]propan-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H30FN3O3
assistant