211820

Appears in sequences

• Triangle read by rows: T(n,k) = number of labeled acyclic digraphs with n nodes, containing exactly n+1-k points of in-degree zero (n >= 1, 1<=k<=n).at n=18A058876
• Number of n-node labeled acyclic digraphs with 3 out-points.at n=3A060335
• a(n) = abs(a(n-1) - 3*a(n-2)) with a(1)=a(2)=1.at n=35A192263
• Number of 4 X n 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=10A207950
• Triangular array read by rows. T(n,k) is the number of labeled directed acyclic graphs on [n] with exactly k nodes of indegree 0.at n=24A361718