You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 3-[[(3R)-1-azabicyclo[2.2.2]octan-3-yl]amino]-6-(1H-indol-3-yl)-4H-1,2,4-triazin-5-one;hydrochloride into molecular formula.
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C18H21ClN6O
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