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system
Name the molecular formula for the molecule established as 1-[2-[(2-methyl-2,3-dihydro-1,4-benzoxazin-4-yl)sulfonyl]-6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl]ethanone using the IUPAC nomenclature.
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C18H20N2O4S2
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