You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-ethyl-2-[(1-ethylpyrrolidin-2-yl)methyl]-3-[3-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)propyl]guanidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H37N7
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