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 ethyl 6-(3,4-dihydro-2H-1,5-benzodioxepin-7-ylmethylamino)pyridine-3-carboxylate is given. What is its corresponding molecular formula?
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C18H20N2O4
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