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 8-methoxy-2-methyl-5-(2-pyridin-4-ylethenyl)-3,4-dihydro-1H-pyrido[4,3-b]indole is given. What is its corresponding molecular formula?
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C20H21N3O
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