You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 1'-[(5-chlorothiophen-2-yl)methyl]-5-methoxyspiro[2H-furo[3,2-b]pyridine-3,3'-2H-indole] is given. What is its corresponding molecular formula?
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C20H17ClN2O2S
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