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-benzothiophen-3-yl)-N-methyl-N-(1-methyl-3,4,4a,5,6,7,8,8a-octahydro-2H-quinolin-8-yl)acetamide by IUPAC nomenclature, provide its molecular formula.
user
C21H28N2OS
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