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-amino-2-methyl-1-(3-methyl-1,3,4,6,7,8,9,9a-octahydropyrido[1,2-a]pyrazin-2-yl)butan-1-one by IUPAC nomenclature, provide its molecular formula.
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C14H27N3O
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