Number of connected labeled 2-regular digraphs with n nodes.
A007108
Number of connected labeled 2-regular digraphs with n nodes.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =1a(4) =9a(5) =216a(6) =7560a(7) =357120a(8) =22025430a(9) =1720751760a(10) =166198926600
External references
- oeis: A007108