a(n) = n!*(!n - 1) = n! * Sum_{k=1..n-1} k!.
A217239
a(n) = n!*(!n - 1) = n! * Sum_{k=1..n-1} k!.
Terms
- a(0) =0a(1) =0a(2) =2a(3) =18a(4) =216a(5) =3960a(6) =110160a(7) =4399920a(8) =238412160a(9) =16777031040
External references
- oeis: A217239
A217239
a(n) = n!*(!n - 1) = n! * Sum_{k=1..n-1} k!.