You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-[1-(furan-2-yl)propan-2-yl]-2-[2-(5-phenyl-1,3,4-oxadiazol-2-yl)pyrrol-1-yl]acetamide by IUPAC nomenclature, provide its molecular formula.
user
C21H20N4O3
assistant