You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 4-(3-amino-5-ethyl-4,6-dimethylthieno[2,3-b]pyridine-2-carbonyl)-3-(4-methylphenyl)-2H-oxadiazol-3-ium-5-one into its molecular formula.
user
C21H21N4O3S+
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