You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-ethyl-2-[(3-hydroxy-4-methoxyphenyl)methyl]-3-[(2-methoxy-4-methylphenyl)methyl]guanidine by IUPAC nomenclature, provide its molecular formula.
user
C20H27N3O3
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