You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named [(1R,5S)-8-(1-bromopropan-2-yl)-8-methyl-8-azoniabicyclo[3.2.1]octan-3-yl] 3-hydroxy-2-phenylpropanoate;bromide by IUPAC nomenclature, provide its molecular formula.
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C20H29Br2NO3
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