Number A(n,k) of endofunctions on [n] such that no element has a preimage of cardinality k; square array A(n,k), n>=0, k>=0, read by antidiagonals.
A245405
Number A(n,k) of endofunctions on [n] such that no element has a preimage of cardinality k; square array A(n,k), n>=0, k>=0, read by antidiagonals.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =0a(5) =2a(6) =1a(7) =1a(8) =2a(9) =6a(10) =1a(11) =1a(12) =2a(13) =3a(14) =24a(15) =1a(16) =1a(17) =4a(18) =9a(19) =40a(20) =120a(21) =1a(22) =1a(23) =4a(24) =24a(25) =76a(26) =205a(27) =720a(28) =1a(29) =1
External references
- oeis: A245405