You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-(5-bromothiophen-2-yl)sulfonyl-N-methyl-N-(4-methylphenyl)piperidine-4-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C18H21BrN2O3S2
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