The value of ∑r=115 r2r(r+2)! is equal to

r×2r(r+2)!=(r+2−2)2r(r+2)!=2r(r+1)!−2r+1(r+2)!=−2r+1(r+2)!−2r(r+1)!=−(V(r)−V(r−1))⇒ ∑r=115 r×2r(r+2)!=−(V(15)−V(0))                            =−21617!−22!                            =1−216(17)!