You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (5-aminopyrazin-2-yl)-(1-methyl-2,3,4,4a,5,7,8,8a-octahydro-1,6-naphthyridin-6-yl)methanone by IUPAC nomenclature, provide its molecular formula.
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C14H21N5O
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