41835024domain: NAppears in sequencesTotal dimension of the homology of a free 2-step nilpotent Lie algebra of rank n.at n=6A078973Number of 7Xn 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=11A208146