The given series is:

$4 + 13 + 22 + 31$

This is an arithmetic sequence where the first term $a_1 = 4$ and the common difference $d = 9$ (since $13 - 4 = 9$, $22 - 13 = 9$, and so on).

We can express the general term of an arithmetic sequence as:

$a_n = a_1 + (n - 1) \cdot d$

Substituting the values of $a_1 = 4$ and $d = 9$:

$a_n = 4 + (n - 1) \cdot 9 = 9n - 5$

Thus, the general term is $a_n = 9n - 5$, and the sequence consists of 4 terms. Therefore, the sum can be written in sigma notation as:

$\sum_{n=1}^{4} (9n - 5)$

Would you like more details on sigma notation or how to handle other sequences?

Here are some related questions:

1. How do you find the sum of an arithmetic series?
2. What is the difference between arithmetic and geometric series?
3. Can sigma notation be used for non-arithmetic series?
4. How would the series change if the common difference were different?
5. What are the key properties of sigma notation?

Tip: When writing in sigma notation, always check the pattern of the sequence first—whether it's arithmetic, geometric, or something else!