You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 3-[5-[3-(4,5-dichlorothiophen-2-yl)sulfonyl-2-oxopropyl]pyrazin-2-yl]-7-methyl-1H-quinazoline-2,4-dione by IUPAC nomenclature, provide its molecular formula.
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C20H14Cl2N4O5S2
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