Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n} -> {1,2,...,n} that have exactly k nonrecurrent elements; n>=1, 0<=k<=n-1.
A219694
Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n} -> {1,2,...,n} that have exactly k nonrecurrent elements; n>=1, 0<=k<=n-1.
Terms
- a(0) =1a(1) =2a(2) =2a(3) =6a(4) =12a(5) =9a(6) =24a(7) =72a(8) =96a(9) =64a(10) =120a(11) =480a(12) =900a(13) =1000a(14) =625a(15) =720a(16) =3600a(17) =8640a(18) =12960a(19) =12960a(20) =7776a(21) =5040a(22) =30240a(23) =88200a(24) =164640a(25) =216090a(26) =201684a(27) =117649a(28) =40320a(29) =282240
External references
- oeis: A219694