Triangle read by rows: T(n,k) = number of functions from [1,2,...,n] to [1,2,...,n] such that the image contains exactly k elements (0<=k<=n).
A090657
Triangle read by rows: T(n,k) = number of functions from [1,2,...,n] to [1,2,...,n] such that the image contains exactly k elements (0<=k<=n).
Terms
- a(0) =1a(1) =0a(2) =1a(3) =0a(4) =2a(5) =2a(6) =0a(7) =3a(8) =18a(9) =6a(10) =0a(11) =4a(12) =84a(13) =144a(14) =24a(15) =0a(16) =5a(17) =300a(18) =1500a(19) =1200a(20) =120a(21) =0a(22) =6a(23) =930a(24) =10800a(25) =23400a(26) =10800a(27) =720a(28) =0a(29) =7
External references
- oeis: A090657