You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 4-methyl-N-[(R)-(2-methyl-1H-indol-3-yl)-thiophen-2-ylmethyl]pyridin-1-ium-2-amine is given. What is its corresponding molecular formula?
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C20H20N3S+
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