46137322

Appears in sequences

• Number of labeled acyclic digraphs with n nodes containing exactly n-1 points of in-degree zero.at n=21A058877
• a(n) = 2*a(n-1) - a(n-3) for n >= 5, a(0) = 2, a(1) = 4, a(2) = 7, a(3) = 12, a(4) = 22.at n=34A289107