You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (4-chlorophenyl)-[3-(dimethylamino)-6,7-dimethoxy-3,4-dihydro-2H-quinolin-1-yl]methanone by IUPAC nomenclature, provide its molecular formula.
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C20H23ClN2O3
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