Item 1.
This is the sequence from Example 2.2.6, in which we found a closed formula by recognizing the sequence as the sequence of partial sums of an arithmetic sequence. Indeed, the sequence of first differences is \(1,4,7, 10, 13,\ldots\text{,}\) which itself has differences \(3,3,3,3,\ldots\text{.}\) Thus \(2, 3, 7, 14, 24, 37,\ldots\) is a \(\Delta^2\)-constant sequence.in-context