33077327domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumber of rooted unlabeled trees on n nodes having a primary branch.at n=20A027415Number of connected functions on n points with a loop of length 2.at n=20A027852Number of rooted unlabeled trees where the root node has degree 2 and both branches are distinct.at n=21A217420Prime numbersat n=2036099