1. an= suma de n , k=1 ∑ [latex] \frac{1}{(k+1)(k+3)} [/latex] , an=? 2. an= suma de n, k=1 ∑[latex] \frac{1}{k(k+1)(k+2)} [/latex] , an=? 3.an=[latex] \frac{1}{2!} + \frac{2}{3!}+ \frac{3}{4!}+...+ \frac{n}{(n+1)!} [/latex] , an=?