41877722domain: NAppears in sequencesTriangle read by rows: T(n,k) is the number of set partitions of the set {1,2,...,n} (or of any n-set) containing k blocks of size 3 (0<=k<=floor(n/3)).at n=40A124503Number of partitions of an n-set without blocks of size 3.at n=14A124504