You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(1R)-1-[3-(4-chlorophenyl)-1,2,4-oxadiazol-5-yl]-3-methylsulfonylpropyl]isoindole-1,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H16ClN3O5S
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