Number of functions f: {1, 2, ..., n} --> {1, 2, ..., n} such that f(1) != f(2), f(2) != f(3), ..., f(n-1) != f(n), f(n) != f(1).

A118537

Number of functions f: {1, 2, ..., n} --> {1, 2, ..., n} such that f(1) != f(2), f(2) != f(3), ..., f(n-1) != f(n), f(n) != f(1).

Terms

    a(0) =2a(1) =6a(2) =84a(3) =1020a(4) =15630a(5) =279930a(6) =5764808a(7) =134217720a(8) =3486784410a(9) =99999999990

External references