You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N'-[2-[(3,5-dichlorophenyl)carbamoyl]-7-methoxyindol-1-yl]-N-(2-methoxyethyl)oxamide by IUPAC nomenclature, provide its molecular formula.
user
C21H20Cl2N4O5
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