Number of sequences of balls colored with at most n colors such that exactly one ball is of a color seen earlier in the sequence.
A281912
Number of sequences of balls colored with at most n colors such that exactly one ball is of a color seen earlier in the sequence.
Terms
- a(0) =1a(1) =8a(2) =57a(3) =424a(4) =3425a(5) =30336a(6) =294553a(7) =3123632a(8) =36003969a(9) =448816600a(10) =6022033721a(11) =86587079448
External references
- oeis: A281912