You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [1-(2-cyclopentylethyl)-6-methyl-4-methylidene-2,3,4a,5,6,7,7a,7b-octahydro-1aH-cyclopropa[e]azulen-1-yl]methanamine by IUPAC nomenclature, provide its molecular formula.
user
C21H35N
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