$$a * b = \frac{1}{ab} + 1 \Rightarrow \sum_{n = 1}^{2013} n * (n + 1) =$$

A

$$2013-\frac{1}{2013}$$

B

$$2014-\frac{1}{2014}$$

C

$$\frac{-1}{2014}$$

D

$$2013-\frac{1}{2014}$$