You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance N-(4-ethoxy-3-methoxyphenyl)-2,3,3a,4,5,6,7,7a-octahydro-1H-indole-2-carboxamide .
user
C18H26N2O3
assistant