209527

Appears in sequences

• Number of different quasi-orders (or topologies, or transitive digraphs) with n labeled elements.at n=6A000798
• Partial sums of A211681.at n=19A213299
• Triangular array read by rows: T(n,k) is the number of transitive relations on {1,2,...,n} that have exactly k reflexive points, n>=0, 0<=k<=n.at n=27A245767
• Triangular array read by rows. T(n,k) is the number of idempotent Boolean relation matrices on [n] with exactly k reflexive points, n >= 0, 0 <= k <= n.at n=27A360984
• 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=27A369776