130824

Appears in sequences

• Number of connected (3,n)-hypergraphs (without empty edges).at n=7A114935
• a(n) is the number of terms of A000057 in [10^n].at n=6A373774
• On a 2 X n grid of vertices, draw a circle through every unordered triple of non-collinear vertices: a(n) is the number of distinct (finite) regions created.at n=9A384702