How can the following be calculated? How can the following series be calculated?
$$S=1+(1+2)+(1+2+3)+(1+2+3+4)+\cdots+(1+2+3+4+\cdots+2011)$$

Hints: useful formulas are
$$\begin{eqnarray*} \sum_{k=1}^N 1 = N \\
\sum_{k=1}^N k = \frac{N(N+1)}{2}\\
\sum_{k=1}^N k^2 = \frac{N(N+1)(2N+1)}{6}\end{eqnarray*}$$
