Triangular array read by rows. T(n,k) is the number of functional digraphs on {1,2,...,n} such that no node is at a distance greater than one from a cycle and there are k recurrent elements whose preimage contains only one element, n>=0, 0<=k<=n.
A220222
Triangular array read by rows. T(n,k) is the number of functional digraphs on {1,2,...,n} such that no node is at a distance greater than one from a cycle and there are k recurrent elements whose preimage contains only one element, n>=0, 0<=k<=n.
Terms
- a(0) =1a(1) =0a(2) =1a(3) =2a(4) =0a(5) =2a(6) =3a(7) =12a(8) =0a(9) =6a(10) =28a(11) =24a(12) =72a(13) =0a(14) =24a(15) =125a(16) =400a(17) =180a(18) =480a(19) =0a(20) =120a(21) =1146a(22) =2220a(23) =4680a(24) =1440a(25) =3600a(26) =0a(27) =720a(28) =8827a(29) =29064
External references
- oeis: A220222