Number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contains 4 fixed elements.
A126780
Number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contains 4 fixed elements.
Terms
- a(0) =24a(1) =360a(2) =5880a(3) =109200a(4) =2298744a(5) =54313560a(6) =1425878520a(7) =41215616640
External references
- oeis: A126780