You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 1-(1-benzothiophen-3-ylmethyl)-9-methyl-6,8,9,9a-tetrahydropyrazino[2,1-c][1,2,4]oxadiazine-4,7-dione by IUPAC nomenclature, provide its molecular formula.
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C16H17N3O3S
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