Triangular array read by rows: T(n,k) is the number of pre-orders on an n-set with exactly k connected components in its digraph representation, n>=1, 1<=k<=n.
A247232
Triangular array read by rows: T(n,k) is the number of pre-orders on an n-set with exactly k connected components in its digraph representation, n>=1, 1<=k<=n.
Terms
- a(0) =1a(1) =3a(2) =1a(3) =19a(4) =9a(5) =1a(6) =233a(7) =103a(8) =18a(9) =1a(10) =4851a(11) =1735a(12) =325a(13) =30a(14) =1a(15) =158175a(16) =43201a(17) =7320a(18) =785a(19) =45a(20) =1a(21) =7724333a(22) =1567783a(23) =218491a(24) =22960a(25) =1610a(26) =63a(27) =1a(28) =550898367a(29) =82142943
External references
- oeis: A247232