Find the closed formula for each of the following sequences by relating them to a well known sequence. Assume the first term given is \(a_1\text{.}\)

1. \(\displaystyle 2, 5, 10, 17, 26, \ldots\)

2. \(\displaystyle 0, 2, 5, 9, 14, 20, \ldots\)

3. \(\displaystyle 8, 12, 17, 23, 30,\ldots\)

4. \(\displaystyle 1, 5, 23, 119, 719,\ldots\)