You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 2-[1-[(4aS,8aS)-4-(pyridin-4-ylmethyl)-3,4a,5,7,8,8a-hexahydro-2H-pyrido[4,3-b][1,4]oxazin-6-yl]cyclobutyl]acetic acid by IUPAC nomenclature, provide its molecular formula.
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C19H27N3O3
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