1. The problem statement, all variables and given/known data 1.1!+2.2!+3.3!.......n terms 2. Relevant equations 3. The attempt at a solution The first part of every term is in AP whose cd is 1. Also the nth term of this series is given as n.n! If I expand it it becomes n.n(n-1)(n-2).......1 Now [itex]S_n=\sum t_n \\ = \sum n.n(n-1)(n-2)......1 [/itex] But now how do I compute this summation?