Triangular array read by rows. T(n,k) is the number of labeled relations on n elements with exactly k vertices of indegree and outdegree = 0.
A217436
Triangular array read by rows. T(n,k) is the number of labeled relations on n elements with exactly k vertices of indegree and outdegree = 0.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =13a(4) =2a(5) =1a(6) =469a(7) =39a(8) =3a(9) =1a(10) =63577a(11) =1876a(12) =78a(13) =4a(14) =1a(15) =33231721a(16) =317885a(17) =4690a(18) =130a(19) =5a(20) =1a(21) =68519123173a(22) =199390326a(23) =953655a(24) =9380a(25) =195a(26) =6a(27) =1a(29) =479633862211a(30) =697866141
External references
- oeis: A217436