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What is the molecular formula of the molecule identified by methyl (1R,9R,10S,12R,19R,20R)-20-methyl-8-aza-16-azoniahexacyclo[10.6.1.19,12.01,9.02,7.016,19]icosa-2,4,6,13-tetraene-10-carboxylate ?
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C21H25N2O2+
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