Find the next two terms in this sequence. The first five numbers of the sequence are the following ones:
1, 2, 6, 15, 31, ..., ...
Target:
What I would like to know is the general formula of the sequence. 
Solution:
The numbers are 56 and 92.

The $(n+1)^\text{th}$ term of the sequence is given by:
\begin{equation}
\frac{(n+2)(2n^2-n+3)}{6}. 
\end{equation}
This is sequence number A056520 on the Online Encyclopedia of Integer Sequences (see http://oeis.org/A056520).
