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 N-[[4-[(3-methoxyphenyl)methyl]-3,4a,5,6,7,7a-hexahydro-2H-cyclopenta[b][1,4]oxazin-7-yl]methyl]pyrazine-2-carboxamide into its molecular formula.
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C21H26N4O3
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