642779354

Appears in sequences

• Number of different quasi-orders (or topologies, or transitive digraphs) with n labeled elements.at n=8A000798
• Triangular array read by rows. T(n,k) is the number of inequivalent (as defined below) transitive binary relations R on [n] such that |domain(R intersect R^(-1))| = k, n>=0, 0<=k<=n.at n=44A369776