You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2-ethylpiperidin-1-yl)-[6-(2-methyl-2,3-dihydroindole-1-carbonyl)pyridin-2-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H27N3O2
assistant