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-[7-(2,3-dihydro-1,4-benzodioxin-6-yl)-2-ethylsulfanyl-5-methyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidin-6-yl]ethanone by IUPAC nomenclature, provide its molecular formula.
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C18H20N4O3S
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