Number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contain two fixed elements.

A126778

Number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contain two fixed elements.

Terms

    a(0) =2a(1) =12a(2) =110a(3) =1320a(4) =19502a(5) =341796a(6) =6927230a(7) =159338640a(8) =4100173022a(9) =116692730220

External references