You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(4-tert-butylphenyl)-N-[2-(cyclopentylamino)-2-oxo-1-pyridin-3-ylethyl]but-2-ynamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H31N3O2
assistant