62960domain: NAppears in sequencesa(n) = n*(7*n^2-4)/3.at n=30A063521Number of irreducible or connected partial orders on {1,2,...,n} that are contained in the usual linear order (i.e., xRy => x < y).at n=7A323502G.f. satisfies A(x) = 1 + x / (1 - x*A(x))^5.at n=8A365115