You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2,4-dichlorophenyl)-2-(2,3-dihydro-1,4-benzodioxin-6-ylsulfonyl)-3,4-dihydro-1H-pyrrolo[1,2-a]pyrazine is the IUPAC name of a molecule. Please give its molecular formula.
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