You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name 2-(2-fluorophenyl)sulfonyl-3-methyl-1,3,4,6,7,8,9,9a-octahydropyrido[1,2-a]pyrazine into its molecular formula.
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C15H21FN2O2S
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