You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-O-tert-butyl 6a-O-methyl (2S,3S,3aS,6aS)-2-(4-chlorophenyl)-2,3,3a,4,5,6-hexahydro-1H-cyclopenta[b]pyrrole-3,6a-dicarboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H26ClNO4
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