You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-amino-4-(furan-3-yl)-6-(1-methylsulfonylpiperidin-2-yl)thieno[2,3-b]pyridine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H20N4O4S2
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