179643domain: NAppears in sequencesNumber of block permutations on an n-set.at n=6A023997Number of partitions of the set {1,2,...,n} having no blocks with all entries of the same parity.at n=12A124425G.f. A(x) satisfies: A(x)^3 - 3*A(x)^4 = A(x^3).at n=9A274396