You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1'-(3-chloro-1H-indole-6-carbonyl)-5-methoxyspiro[3H-chromene-2,4'-piperidine]-4-one by IUPAC nomenclature, provide its molecular formula.
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C23H21ClN2O4
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