Number of one-to-one functions f from [n] to [2n] where f(x) may not be equal to x or to 2n+1-x.
A272261
Number of one-to-one functions f from [n] to [2n] where f(x) may not be equal to x or to 2n+1-x.
Terms
- a(0) =1a(1) =0a(2) =4a(3) =40a(4) =576a(5) =10528a(6) =233920a(7) =6124032a(8) =184656640a(9) =6302821888a(10) =240245858304
External references
- oeis: A272261