Number of sequences over the alphabet of n symbols of length 2n which have n distinct symbols. Also number of placements of 2n balls into n cells where no cell is empty.
A210029
Number of sequences over the alphabet of n symbols of length 2n which have n distinct symbols. Also number of placements of 2n balls into n cells where no cell is empty.
Terms
- a(0) =1a(1) =14a(2) =540a(3) =40824a(4) =5103000a(5) =953029440a(6) =248619571200
External references
- oeis: A210029