246218domain: NAppears in sequencesa(n) = 2*a(n-1) + (n-2)*a(n-2) with a(0) = 1, a(1) = 2.at n=11A027412Number of set partitions of the multiset consisting of one copy each of x_1, x_2, ..., x_n, and 2 copies each of y_1 and y_2.at n=7A322764Number of partitions of the (n+9)-multiset {1,2,...,n,1,2,...,9}.at n=2A346886